Delayed release drug formulation

ABSTRACT

Delayed release of a drug to the colon is achieved from a delayed release formulation comprising a core and a coating for the core. The core comprises a drug and the coating comprises an inner layer and an outer layer. The outer layer comprises a mixture of a first polymeric material which is susceptible to attack by colonic bacteria, and a second polymeric material which has a pH threshold at about pH 5 or above. The inner layer comprises a third polymeric material which is soluble in intestinal fluid or gastrointestinal fluid, said third polymeric material being selected from an at least partially neutralized polycarboxylic acid and a non-ionic polymer. In embodiments in which the third polymeric material is a non-ionic polymer, the inner layer comprises at least one of a buffer agent and a base. Advantages of formulations according to the present invention include accelerated release of the drug when exposed to colonic conditions and reduction or elimination of a food and/or alcohol effect on drug release after administration.

The present invention relates to a delayed release formulation with acore comprising a drug and a delayed release coating. In particular, itrelates to a delayed release formulation for delivering a drug to thecolon.

The targeting of drugs to the intestine is well known and has been knownfor over one hundred years. Commonly, the target of the drugs is thesmall intestine although the colon can be utilised as a means ofachieving local therapy or systemic treatment. The requirements for thecoatings on the drugs are different depending on the target site. Inorder to reach the colon, it is necessary for the drugs to pass throughthe small intestine, and therefore it is a requirement that a delayedrelease coating intended to release the drug in the colon does notrelease the drug in the small intestine.

Coated products for release in the small intestine commonly use polymercoatings which dissolve or disintegrate in a pH dependent manner. In thelow pH environment of the stomach, the polymer coating is insoluble.However, on reaching the small intestine, the pH rises to 5 and aboveand the polymeric coating dissolves or disintegrates. A commonly usedcoating is one containing ionizable carboxylic groups. At higher pHlevels, the carboxylic groups ionize, allowing the polymer coatings todisintegrate or dissolve. Common polymers of this type which are usedinclude Eudragit® L and Eudragit® S.

Various methods of improving the release in the small intestine byensuring an earlier release of the drug are known. US2008/0200482 is oneof a number of references which discloses partially neutralizing thecarboxylic groups in order to reduce the pH at which disintegrationoccurs. WO2008/135090 discloses a tablet with an inner coat of partiallyneutralized material and an outer coat with less or no neutralization.This is said to result in disintegration at an earlier time point whentransferred from the stomach.

Release of drugs in the colon typically requires an alternativeapproach. The colon is susceptible to a number of disease states,including inflammatory bowel disease, irritable bowel syndrome,constipation, diarrhea, infection and carcinoma. In such conditions,drug targeting to the colon would maximise the therapeutic effectivenessof the treatment. The colon can also be utilised as a portal for theentry of drugs into the systemic circulation. Various formulations havebeen developed for colonic drug delivery, including pro-drugs as well asformulated dosage forms, with the latter being more popular since theconcept once proved can be applied to other drugs.

The higher bacterial population in the colon has also been exploited indeveloping colonic drug delivery dosage forms through the use, ascarrier materials, of naturally occurring polysaccharides thatconstitute substrates for the numerous enzymes of the resident colonicbacteria. These materials are able to pass through the uppergastrointestinal regions intact but are digested upon entry into thecolon. Those studied so far include amylose, pectin, chitosan andgalactomannan.

Amylose is resistant to digestion by the enzymes of the uppergastrointestinal tract. It is, however, fermented in the colon byα-amylase enzymes produced by over half of the 400 bacteria speciesresident in the colon.

One major attraction of using polysaccharides in this bacterial enzymeapproach to colonic drug delivery is that materials used are of foodgrade and so would be safe for use in humans. They are usually appliedas coatings or incorporated in the core material as a matrix carrier,and their digestion on entry into the colon by the colonic bacterialenzymes leads to the release of the drug load. An example of such aformulation, which employs an amylose coating, is disclosed inEP0343993A (BTG International Limited).

A major limitation with these naturally occurring materials, however, isthat they swell excessively in aqueous media leading to leaching of thedrug load in the upper gastrointestinal regions. To circumvent thisproblem, the naturally occurring materials have been utilised in amixture with various impermeable materials.

EP0502032A (British Technology Group Ltd) teaches the use of an outercoating comprising a film forming cellulose or acrylate polymer materialand amorphous amylose for a tablet comprising an active compound. Thepolymer material used is a pH independent release polymer material.

An article in Journal of Controlled Release (Milojevic et al; 38;(1996); 75-84) reports the results of investigations concerning theincorporation of a range of insoluble polymers into an amylose coatingin order to control amylose swelling. A range of cellulose and acrylatebased co-polymers are assessed, and a commercially available ethylcellulose (Ethocel®) is found to control the swelling most effectively.A pH dependent soluble coating of Eudragit® L100 is employed but only ina multi-layer system comprising a bioactive coated with an inner coatingof amylose and then an outer coating of Eudragit® L100.

A further amylose-based coating composition is disclosed in WO99/21536A(BTG International Limited). The coating composition comprises a mixtureof amylose and a water insoluble pH independent film-forming polymerwhich is formed from a water-insoluble cellulosic or acrylate polymermaterial.

WO99/25325A (BTG International Limited) also discloses a delayed releasecoating comprising amylose and (preferably) ethyl cellulose oralternatively an insoluble acrylate polymer. The coating compositionalso includes a plasticiser and the method finds particular applicationin the preparation of dosage forms comprising active materials that areunstable at temperatures in excess of 60° C., as the composition isformed at lower temperatures than this.

WO03/068196A (Alizyme Therapeutics Ltd) discloses a specific delayedrelease coating for the bioactive prednisolone sodium metasulphobenzoatecomprising glassy amylose, ethyl cellulose and dibutyl sebacate.

The use of polysaccharides other than amorphous amylose in a delayedrelease coating is disclosed in GB2367002 (British Sugar PLC). Examplesinclude guar gum, karaya gum, gum tragacanth and xanthan gum.Microparticles of these polysaccharides are dispersed in awater-insoluble film-forming polymer matrix formed for example from acellulose derivative, an acrylic polymer or a lignin.

WO01/76562A (Tampereen Patenttitoimisto Oy) discloses a peroralpharmaceutical formulation containing a drug and a chitosan (apolysaccharide obtained from chitin) for controlling its release. Thedrug and the chitosan are mixed into a homogeneous mechanical powdermixture which is granulated and then optionally tabletised. Thegranulation may be performed with an enteric polymer (such as acopolymer of methacrylic acid) or the granules may be provided with aporous enteric coating.

WO2004/052339A (Salvona LLC) discloses a pH dependent drug releasesystem which is a free-flowing powder of solid hydrophobic nano-spherescomprising a drug encapsulated in a pH-sensitive micro-sphere. Thenano-spheres are formed from the drug in combination with a waxmaterial, and the pH-sensitive micro-sphere formed from a pH-sensitivepolymer (such as a Eudragit® polymer) in combination with awater-sensitive material such as a polysaccharide.

An article in the European Journal of Pharmaceutical Sciences (Akhgariet al; 28; Mar. 2006; 307-314) reports the results of investigationsinto the use of certain polymethacrylate polymers to, inter alia,control the swelling of inulin. The polymethacrylate polymers testedwere Eudragit® RS; Eudragit® RL; 1:1 mixtures of Eudragit® RS andEudragit® RL; Eudragit® FS; and 1:1 mixtures of Eudragit® RS andEudragit® S.

U.S. Pat. No. 5,422,121 (Röhm GmbH) discloses an oral dosage form havinga core containing at least one active ingredient enclosed within a shellmaterial which comprises a polysaccharide that decomposes in the colonin admixture with a film-forming polymer. The ratio by weight ofpolysaccharide to film forming polymer is from 1:2 to 5:1, preferablyfrom 1:1 to 4:1. Premature diffusion of the active ingredient from thecore can be suppressed using a gastric resistant isolating layer. Thereference exemplifies inter alia tablets having an inner isolating layerof Eudragit® L30D with an outer layer comprising Eudragit® L30D and guargum (Example 2).

WO96/36321A discloses an oral dosage form comprising a core containingbisacodyl, and an enteric polymer coating for the core, the coatingcomprising at least one inner coating layer and an outer coating layer.The or each the inner coating layer is an enteric polymer that begins todissolve in an aqueous medium at a pH from about 5 to about 6.3, and theouter coating layer is an enteric polymer that begins to dissolve in anaqueous medium at a pH from about 6.8 to about 7.2. The enteric polymercoating materials for the inner layer(s) are selected from the groupconsisting of cellulose acetate phthalate; cellulose acetatetrimellitate; hydroxypropyl methylcellulose phthalate; hydroxypropylmethylcellulose acetate succinate; polyvinyl acetate phthalate;poly(methacrylic acid, methyl methacrylate) 1:1; poly(methacrylic acid,ethyl acrylate) 1:1; and compatible mixtures thereof.

WO2007/122374A discloses a colonic drug delivery formulation in which amixture of a pH dependent film forming polymeric material and apolysaccharide such as starch is used. Although it is known that thisformulation shows delayed release followed by a relatively quick releaseof the drug, it would be preferred if the drug release was quicker inthe colon.

In accordance with a first aspect of the present invention, there isprovided a delayed release drug formulation for oral administration todeliver a drug to the colon of a subject, said formulation comprising acore and a coating for the core, the core comprising a drug and thecoating comprising an outer layer and an inner layer, wherein the outerlayer comprises a mixture of a first polymeric material which issusceptible to attack by colonic bacteria and a second polymericmaterial which has a pH threshold at about pH 5 or above, and whereinthe inner layer comprises a third polymeric material that is soluble inintestinal fluid or gastrointestinal fluid, said third polymericmaterial being selected from the group consisting of a polycarboxylicacid polymer that is at least partially neutralised, and a non-ionicpolymer, provided that, where said third polymeric material is anon-ionic polymer, said inner layer comprises at least one additiveselected from a buffer agent and a base.

The Inventors have discovered that a coating having an inner layercomprising a polymer that is soluble in intestinal fluid orgastrointestinal fluid, e.g. a partially or fully neutralisedpolycarboxylic acid polymer, and an outer layer of a mixture of a firstpolymeric material susceptible to attack by colonic bacteria, e.g. apolysaccharide, and a second polymeric material which has a pH thresholdat about pH 5 or above, e.g. a polycarboxylic acid polymer of the sametype as the polymer of the inner layer but either non-neutralised orpartially neutralised to a lower extent than the third polymericmaterial, has superior colonic-release properties over comparativecoatings designed for site-specific release in the colon. In thisconnection, drug release from formulations according to the presentinvention appears to be accelerated in the colon when compared tocomparative colonic release formulations. Without wishing to be bound byany particular theory, the Inventors believe that, once intestinal fluidor gastrointestinal fluid penetrates the outer layer, the inner layerbegins to dissolve before the outer layer to form a fluid region betweenthe core and the outer layer. The fluid region not only facilitatesdissolution and/or disintegration of the outer layer from the inside,but also softens and begins to break up the core so that, when the outerlayer degrades, the drug is released from the core more quickly.

It is preferred that the first polymeric material comprises at least onepolysaccharide selected from the group consisting of starch; amylose;amylopectin; chitosan; chondroitin sulfate; cyclodextrin; dextran;pullulan; carrageenan; scleroglucan; chitin; curdulan and levan. It isparticularly preferred that the first polymeric material is starch.

In preferred embodiments, the second polymeric material is an anionicpolymeric material, and more preferably an anionic copolymer of a(meth)acrylic acid and a (meth)acrylic acid alkyl ester.

The third polymeric material is preferably an anionic polymeric materialand more preferably an at least partially neutralised, preferably fullyneutralised, copolymer of a (meth)acrylic acid and a (meth)acrylic acidalkyl ester.

In a preferred embodiment, the second polymeric material is the sametype of copolymer of a (meth)acrylic acid and a (meth)acrylic acid alkylester as the third polymeric material prior to neutralisation.

In a particularly favourable embodiment, the present invention relatesto a delayed release drug formulation comprising a core and a coatingfor the core, the core comprising a drug; and the coating comprising anouter layer and an inner layer, wherein the outer layer comprises amixture of starch and a copolymer of a (meth)acrylic acid and a(meth)acrylic acid C₁₋₄ alkyl ester; and the inner layer comprises afully neutralized copolymer of a (meth)acrylic acid and a (meth)acrylicacid C₁₋₄ alkyl ester.

Some materials that are susceptible to attack by colonic bacteria, e.g.amylose, swell when exposed to aqueous fluid, e.g. gastrointestinalfluid. Such swelling is undesirable since it results typically inpremature release of the drug. The swelling is controlled by theinclusion of a pH dependent material having a pH threshold of pH 5 orabove.

A further technical advantage of the present invention (compared, forexample, to the formulation disclosed in WO01/76562A) is thatsubstantially no drug is released for an extended period (that is,whilst the coating is intact and is being dissolved/disintegrated),following which the drug is released relatively quickly. This is incontrast to homogeneous tablets from which the drug release profile isgradual from the outset rather than delayed then pulsatile.

A yet further technical advantage of the present invention compared toWO2007/122374A is accelerated release of the drug once the formulationis exposed to the conditions of the colonic environment.

First Polymeric Material

The first polymeric material typically comprises a polysaccharide,preferably containing a plurality of glucose units, e.g. apolyglucoside. In a preferred embodiment, the polysaccharide is at leastone polysaccharide selected from the group consisting of starch;amylose; amylopectin; chitosan; chondroitin sulfate; cyclodextrin;dextran; pullulan; carrageenan; scleroglucan; chitin; curdulan andlevan. It is further preferred that the polysaccharide is starch,amylose or amylopectin, most preferably starch.

The person skilled in the art is capable of determining whether apolymeric material is susceptible to attack by colonic bacteria usingtechniques comprising part of the common general knowledge. For example,a pre-determined amount of a given material could be exposed to an assaycontaining an enzyme from a bacterium found in the colon and the changein weight of the material over time may be measured.

The polysaccharide is preferably starch. Starches are usually extractedfrom natural sources such as cereals; pulses; and tubers. Suitablestarches for use in the present invention are typically food gradestarches and include rice starch; wheat starch; corn (or maize) starch;pea starch; potato starch; sweet potato starch; tapioca starch; sorghumstarch; sago starch; and arrow root starch. The use of maize starch isexemplified below.

Starch is typically a mixture of two different polysaccharides, namelyamylose and amylopectin. Different starches may have differentproportions of these two polysaccharides. Most natural (unmodified)maize starches have from about 20 wt % to about 30 wt % amylose with theremainder being at least substantially made up of amylopectin. Starchessuitable for use in the present invention typically have at least 0.1 wt%, e.g. at least 10% or 15%, preferably at least 35 wt %, amylose.

“High amylose” starches, i.e. starches having at least 50 wt % amylose,are suitable. Particularly suitable starches have from about 55 wt % toabout 75 wt %, e.g. about 60 wt % or about 70 wt % amylose. Inparticular, starches having from about 50 wt % to about 60 wt % amyloseare also suitable,

Starches suitable for use in the present invention may have up to 100%amylopectin, more typically from about 0.1 wt % to about 99.9 wt %amylopectin. “Low amylose” starches, i.e. starches having no more than50 wt % amylose and at least 50 wt % amylopectin, e.g. up to 75 wt %amylopectin and even as much as up to 99 wt % amylopectin, are stillsuitable. The starch may be, for example, unmodified waxy corn starch.This typically comprises about 100% amylopectin.

Preferred starches have no more than 50 wt % amylopectin. As indicatedabove, particularly suitable starches are “high amylose” starches whichhave from about 25 wt % to about 45 wt % amylopectin, e.g. about 30 wt %or about 40 wt % amylopectin. In particular, starches having from about40 wt % to about 50 wt % amylopectin are also suitable.

The person skilled in the art is capable of determining the relativeproportions of amylose and amylopectin in any given starch. For example,near-infrared (“NIR”) spectroscopy could be used to determine theamylose and amylopectin content of a starch using calibration curvesobtained by NIR using laboratory-produced mixtures of known amounts ofthese two components. Further, starch could be hydrolysed to glucoseusing amyloglucosidase. A series of phosphorylation and oxidationreactions catalysed by enzymes result in the formation of reducednicotinamide adenine dinucleotide phosphate (“NADPH”). The quantity ofNADPH formed is stoichiometric with the original glucose content.Suitable test kits for this procedure are available (e.g., R-BiopharmGmbH, Germany). Another method that could be used involves subjectingthe coating to digestion by bacterial enzymes, e.g. α-amylase, toproduce short chain fatty acids (“SCFA”) which can be quantified bygas-liquid chromatography using a capillary column.

Preferred starches have amylose in its glassy form although amylose inits amorphous form may also be used in conjunction with the presentinvention.

Preferred starches are “off-the-shelf” starches, i.e. starches whichrequire no processing prior to use in the context of the presentinvention. Examples of particularly suitable “high amylose” starchesinclude Hylon™ VII (National Starch, Germany), Eurylon™ 6 (or VI) orAmylo NI-460 or Amylo N-400 (Roquette, Lestrem, France), or Amylogel03003 (Cargill, Minneapolis, USA) all of which are examples of a maizestarch having from about 50 wt % to about 75 wt % amylose.

Second Polymeric Material

The present invention involves the use of a second polymeric materialthat dissolves in a pH dependent manner. The second material is a filmforming polymer that is pH sensitive, i.e. has a “pH threshold” which isthe pH below which it is insoluble in aqueous media and at or abovewhich it is soluble in aqueous media. Thus, the pH of the surroundingmedium triggers dissolution of the second polymeric material and none(or essentially none) of the second polymeric material dissolves belowthe pH threshold. Once the pH of the surrounding medium reaches (orexceeds) the pH threshold, the second polymeric material becomessoluble.

Throughout the specification, the term “insoluble” is used to mean that1 g of a polymeric material requires more than 10,000 ml of solvent or“surrounding medium” to dissolve at a given pH. In addition, the term“soluble” is used to mean that 1 g of a polymeric material requires lessthan 10,000 ml, preferably less than 5,000 ml, more preferably less than1000 ml, even more preferably less than 100 ml or 10 ml of solvent orsurrounding medium to dissolve at a given pH.

By “surrounding medium”, the Inventors mean gastric fluid and intestinalfluid, or an aqueous solution designed to recreate in vitro gastricfluid or intestinal fluid.

The normal pH of gastric juice is usually in the range of pH 1 to 3. Thesecond polymeric material is insoluble below pH 5 and soluble at aboutpH 5 or above and, thus, is usually insoluble in gastric juice. Such amaterial may be referred to as a gastro-resistant material or an“enteric” material.

The second polymeric material has a pH threshold of pH 5 or above, e.g.about pH 5.5 or above, preferably about pH 6 or above and morepreferably about pH 6.5 or above. The second polymeric materialtypically has a pH threshold of no more than about pH 8, e.g. no morethan about pH 7.5 and preferably no more than about pH 7.2. Preferably,the second polymeric material has a pH threshold within the range of pHfound in intestinal fluid. The pH of intestinal fluid may vary from oneperson to the next, but in healthy humans is generally from about pH 5to 6 in the duodenum, from about 6 to 8 in the jejunum, from about 7 to8 in the ileum, and from about 6 to 8 in the colon. The second polymericmaterial preferably has a pH threshold of about 6.5, i.e. is insolublebelow pH 6.5 and soluble at about pH 6.5 or above, and more preferablyhas a pH threshold of about 7, i.e. is insoluble below pH 7 and solubleat about pH 7 or above.

The pH threshold at which a material becomes soluble may be determinedby a simple titration technique which would be part of the commongeneral knowledge to the person skilled in the art.

The second polymeric material is typically a film-forming polymericmaterial such as a polymethacrylate polymer, a cellulose polymer or apolyvinyl-based polymer. Examples of suitable cellulose polymers includecellulose acetate phthalate (CAP); cellulose acetate trimellitate (CAT);and hydroxypropylmethylcellulose acetate succinate (HPMC-AS). Examplesof suitable polyvinyl-based polymers include polyvinyl acetate phthalate(PVAP).

The second material is preferably an “anionic” polymeric material, i.e.a polymeric material containing groups that are ionisable in aqueousmedia to form anions (see below), and more preferably a co-polymer of a(meth)acrylic acid and a (meth)acrylic acid C₁₋₄ alkyl ester, forexample, a copolymer of methacrylic acid and methacrylic acid methylester. Such a polymer is known as a poly(methacrylic acid/methylmethacrylate) co-polymer. Suitable examples of such co-polymers areusually anionic and not sustained release polymethacrylates. The ratioof carboxylic acid groups to methyl ester groups (the “acid:esterratio”) in these co-polymers determines the pH at which the co-polymeris soluble. The acid:ester ratio may be from about 2:1 to about 1:3,e.g. about 1:1 or, preferably, about 1:2. The molecular weight (“MW”) ofpreferred anionic co-polymers is usually from about 120,000 to 150,000g/mol, preferably about 125,000 g/mol or about 135,000 g/mol.

Preferred anionic poly(methacrylic acid/methyl methacrylate) co-polymershave a molecular weight of about 125,000 g/mol. Suitable examples ofsuch polymers have an acid:ester ratio of about 1:1 and a pH thresholdof about pH 6, or have an acid:ester ratio of about 1:2 and a pHthreshold of about pH 7.

A specific example of a suitable anionic poly(methacrylic acid/methylmethacrylate) co-polymer having a molecular weight of about 125,000g/mol, an acid:ester ratio of about 1:1 and a pH threshold of about pH 6is sold under the trade mark Eudragit® L. This polymer is available inthe form of a powder (Eudragit® L 100), or as an organic solution(12.5%) (Eudragit® L 12.5).

A specific example of a suitable anionic poly(methacrylic acid/methylmethacrylate) co-polymer having a molecular weight of about 125,000g/mol, an acid:ester ratio of about 1:2 and a pH threshold of about pH 7is sold under the trade mark Eudragit® S. This polymer is available inthe form of a powder (Eudragit® S 100) or as an organic solution (12.5%)(Eudragit® S 12.5).

The second polymeric material may be a co-polymer of methacrylic acidand ethyl acrylate. Preferred poly(methacrylic acid/ethyl acrylate)co-polymers have a molecular weight from about 300,000 to 350,000 g/mol,e.g. about 320,000 g/mol. Suitable examples of such co-polymers have anacid:ester ratio of about 1:1 and a pH threshold of about pH 5.5.

A specific example of a suitable anionic poly(methacrylic acid/ethylacrylate) co-polymer is available in the form of a powder and sold underthe trade mark Eudragit® L 100-55, or in the form of an aqueousdispersion (30%) and sold under the trade mark Eudragit® L 30 D-55.

The second polymeric material may be a co-polymer of methyl acrylate,methyl methacrylate and methacrylic acid. Preferred poly(methylacrylate/methyl methacrylate/methacrylic acid) co-polymers have amolecular weight from about 250,000 to about 300,000 g/mol, e.g. about280,000 g/mol. Suitable examples of such co-polymers have a methylacrylate:methyl methacrylate:methacrylic acid ratio of about 7:3:1thereby providing an acid:ester ratio of about 1:10 and a pH thresholdof about pH 7.

A specific example of a suitable anionic poly(methyl acrylate/methylmethacrylate/ethyl acrylate) co-polymer is available in the form of anaqueous dispersion (30%) and is sold under the trade mark Eudragit® FS30 D.

The Eudragit® co-polymers are manufactured and/or distributed by EvonikGmbH, Darmstadt, Germany.

Mixtures of film forming polymer materials may be used as appropriate.For example, the second polymeric material may be a blend of at leasttwo different polymers having a pH threshold of about pH 5 and above.Preferably, the polymers in the blend are different polymethacrylatepolymers. In embodiments where the second polymeric material is a blendof two different polymers having a pH threshold of about pH 5 or above,the polymers may be present in the blend in a polymer weight ratio fromabout 1:99 to about 99:1, .e.g. from about 10:90 to about 90:10, or from25:75 to about 75:25, or from about 40:60 to about 60:40, for exampleabout 50:50.

An example of a suitable mixture would include a mixture, e.g. a 1:1mixture, of Eudragit® L and Eudragit® S. A further example would includea blend, e.g. a 50:50 blend, of Eudragit S and Eudragit FS.

For the avoidance of doubt, the terms “mixture” and “blend” in thecontext of mixtures or blends of polymers forming the second polymericmaterial, are used herein interchangeably.

However, the use of a particular film forming polymer material, e.g. apoly(methacrylic acid/methyl methacrylate) co-polymer, alone ispreferred. The use of Eudragit® S alone as the second polymeric materialis particularly preferred.

Outer Layer

The proportion of the first polymeric material to the second polymericmaterial is typically at least 1:99, e.g. at least 10:90 and preferablyat least 25:75. The proportion is typically no more than 99:1, e.g. nomore than 75:25 and preferably no more than 60:40. In some embodiments,the proportion may be no more than 35:65. In some preferred embodiments,the proportion is from 10:90 to 75:25, e.g. from 10:90 to 60:40 andpreferably from 25:75 to 60:40. In some particularly preferredembodiments, the proportion is from 15:85 to 35:65, e.g. from 25:75 to35:65 and preferably about 30:70. In other particularly preferredembodiments, the proportion is from 40:60 to about 60:40, e.g. about50:50.

The mixture of first and second polymeric materials is preferablysubstantially homogenous.

Optionally, conventional excipients such as those excipients selectedfrom plasticisers for film formation (for example, triethyl citrate),anti-tack agents (such as glyceryl monostearate or GMS) and surfactants(such as polysorbate 80), may be included in amounts up to 30 wt % ofthe final composition of the outer coating preparation.

The thickness of the outer coating of the core is typically from about10 μm to about 150 μm. The thickness of a specific coating will,however, depend on the composition of the coating. For example, coatingthickness is directly proportional to the amount of polysaccharide inthe coating. Thus, in embodiments where the coating comprises highamylose starch and Eudragit™ S at a ratio of about 30:70, the coatingthickness may be from about 70 μm to about 130 μm, and preferably fromabout 90 μm to about 110 μm. The thickness (in μm) for a given coatingcomposition is independent of core size.

The thickness of the outer coating is not related to the size of thecore but is typically equivalent to about 2 mg/cm² to about 10 mg/cm²,preferably from about 2 mg/cm² to about 8 mg/cm², and most preferablyfrom about 4 mg/cm² to about 8 mg/cm², based on the dry weight of thetotal polymeric material, for cores having a diameter from about 5×10⁻⁴m to about 25 mm.

Third Polymeric Material

The formulation according to the present invention additionally has aninner layer which is positioned between the core and the outer layer.The inner layer comprises a third polymeric material which may beinsoluble in gastric fluid and soluble in intestinal fluid, butpreferably is soluble in both gastric fluid and intestinal fluid(referred herein as gastrointestinal fluid).

By “gastric fluid”, the inventors mean the aqueous fluid in the stomachof a mammal, particularly a human. The fluid contains up to about 0.1 Nhydrochloric acid and substantial quantities of potassium chloride andsodium chloride, and plays a key role in digestion by activatingdigestive enzymes and denaturing ingested protein. Gastric acid isproduced by cells lining the stomach and other cells produce bicarbonatewhich acts as a buffer to prevent the gastric fluid from becoming tooacidic.

By “intestinal fluid”, the Inventors mean the fluid in the lumen of theintestine of a mammal, particularly a human. Intestinal fluid is a paleyellow aqueous fluid secreted from glands lining the walls of theintestine. Intestinal fluid includes fluid found in the small intestine,i.e. fluid found in the duodenum (or “duodenal fluid”), fluid found inthe jejunum (or “jejunal fluid”) and fluid found in the ileum (or “ilealfluid”), and fluid found in the large intestine, e.g. “colonic fluid”.

The skilled person can readily determine whether a polymer is soluble ingastric fluid and/or intestinal fluid. If a polymer is soluble in water(or aqueous solution), e.g. a buffer solution) at a pH from 1 to 3, thenthat polymer would typically be soluble in gastric fluid. Similarly if apolymer is soluble in water (or aqueous solution, e.g. a buffersolution) at a pH from 5 to 8, then that polymer would typically besoluble in intestinal fluid. Alternatively, the compositions of gastricfluid and intestinal fluid are known and may be replicated in vitro. Ifa polymer is soluble in artificial gastric fluid or intestinal fluid invitro, then it would typically be soluble in gastric fluid or intestinalfluid respectively in vivo.

Any pharmacologically acceptable water soluble film forming polymersare, in principle, suitable for use as the third polymeric material. Thesolubility of the water soluble polymers may be dependent on pH, i.e.the third polymeric material may be a pH sensitive polymer having a pHthreshold. In such embodiments, the pH threshold of the third polymericmaterial is less than, typically at least 0.5 pH units less than andpreferably from 0.5 to 3.5 pH units less than, the pH threshold of thesecond polymeric material. The pH threshold of the third polymericmaterial is typically from about pH 4.5 to about pH 7.5.

The third polymeric material may be soluble in at least one fluidselected from gastric fluid, duodenal fluid, jejunal fluid and ilealfluid. However, in preferred embodiments, the solubility of the thirdpolymeric material in water is not dependent on pH; at least not withinthe range of pH found in the intestine. In preferred embodiments, thethird polymeric material is soluble in fluid at any point in the stomachand intestine, i.e. in gastrointestinal fluid.

Suitable polymers for use as the third polymeric material preferablycontain groups that are ionisable in aqueous media to form anions. Suchpolymers are known in the art as “anionic” polymers. Suitable anionicpolymers include polycarboxylic acid polymers, i.e. polymers orco-polymers that contain a plurality of carboxylic acid functionalgroups that are ionisable in aqueous media such as intestinal fluid, toform carboxylate anions.

In embodiments in which the third polymeric material is a polycarboxylicacid polymer, it is preferred that the third polymeric material is atleast partially neutralised, i.e. that at least a portion, e.g. at least10%, preferably at least 25%, more preferably at least 50%, and mostpreferably at least 90%, of the carboxylic acid groups in are the formof carboxylate anions. In particularly preferred embodiments, all of thecarboxylic acid groups in the third polymeric material are in the formof carboxylate anions. Such polymers are referred to herein as “fullyneutralised”.

In preferred embodiments, the second and third polymeric materials arebased on the same polycarboxylic acid polymer with the third polymericmaterial having a higher degree of neutralisation than the secondpolymeric material. For example, for a particular polycarboxylic acidpolymer, the second polymeric material may be in non-neutralised formwith the third polymeric material in partially or fully neutralisedform. Alternatively, the second polymeric material may be in partiallyneutralised form, with the third polymeric material also in partiallyneutralised form (although partially neutralised to a greater extent),or in fully neutralised form.

Examples of suitable polycarboxylic acid polymers include celluloseacetate phthalate (CAP), polyvinyl acetate phthalate (PVAP),hydroxypropyl methylcellulose phthalate (HPMCP), hydroxypropylmethylcellulose acetate succinate (HPMC-AS), cellulose acetatetrimellitate (CAT), xanthan gum, alginates and shellac. However, thepolycarboxylic acid polymer is preferably selected from co-polymers of a(meth)acrylic acid and a (meth)acrylic acid alkyl, e.g. C₁₋₄ alkyl,ester and a copolymer of methacrylic acid and methacrylic acid methylester is particularly suitable. Such a polymer is known as apoly(methacrylic acid/methyl methacrylate) co-polymer or a“polymethacrylate”. The ratio of carboxylic acid groups to methyl estergroups (the “acid:ester ratio”) in these co-polymers determines the pHat which the co-polymer is soluble. The acid:ester ratio may be fromabout 2:1 to about 1:3, e.g. about 1:1 or, preferably, about 1:2. Themolecular weight (“MW”) of preferred anionic co-polymers is usually fromabout 120,000 to 150,000, preferably about 125,000 or about 135,000.

Preferred co-polymers for the third polymeric material are discussed indetail in the section above relating to the second polymeric material,and include Eudragit® L; Eudragit® S; Eudragit® FS 30 D; Eudragit®L30D-55; and Eudragit® L100-55.

The exemplary polymers may be used as the third polymeric material innon-neutralised form (provided the pH threshold of the polymer is lessthan the pH threshold of the second polymeric material—see above) or maybe used in at least partially, more preferably fully, neutralised form.

Partially neutralised polymers suitable for use as the third polymericmaterial, and their methods of production, are known in the art, forexample from US2008/0200482A and WO2008/135090A. These polymers may befully neutralised by the addition of further base to the coatingsolutions.

In preferred embodiments, the third polymeric material is an at leastpartially, preferably fully, neutralised co-polymer of (meth)acrylicacid and a (meth)acrylic acid C₁₋₄ alkyl ester. In particularlypreferred embodiments, the third polymeric material is a fullyneutralised co-polymer of (meth)acrylic acid and (meth)acrylic acidmethyl ester, particularly Eudragit® S.

The Inventors have observed that fully neutralised Eudragit® S iscapable of forming a film and is readily and completely soluble in waterindependently of at least the range of pH found in the intestine, e.g.about pH 5 to about pH 8. Fully neutralised Eudragit® S is particularlypreferred for use as the third polymeric material in the presentinvention.

Other polymers suitable for use as the third polymeric material includepharmacologically acceptable non-ionic polymers, i.e. pharmacologicallyacceptable polymers which do not ionise in aqueous media. In theseembodiments, the inner layer additionally comprises at least oneadditive selected from a buffer agent and a base. In particular, theinner layer of these embodiments preferably comprises a base and,optionally, a buffer agent. In preferred embodiments, the inner layercomprises both a buffer agent and a base. Suitable examples of bufferagents and bases are discussed below.

Examples of suitable non-ionic polymers include methylcellulose (MC),hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC),poly(ethyleneoxide)-graft-polyvinylalcohol, polyvinylpyrrolidinone(PVP), polyethylene glycol (PEG) and polyvinylalcohol (PVA).

Mixtures of film forming polymer materials may be used as appropriate.The polymer components in such mixtures may be anionic polymers,non-ionic polymers, or a mixture of anionic and non-ionic polymers. Anexample of a suitable mixture would include a mixture, e.g. a 1:1mixture, of Eudragit® L and Eudragit® S, and a mixture, e.g. a 1:1mixture, of Eudragit® S and HPMC. However, the use of a particular filmforming polymeric material alone, e.g. a poly(methacrylic acid/methylmethacrylate) co-polymer and Eudragit® S in particular, is preferred.

Base

In preferred embodiments, the inner layer comprises at least one base.The purpose of the base is to provide an alkaline environment on theunderside of the outer layer once intestinal fluid begins to penetratethe outer layer. Without being bound by any particular theory, theInventors believe that the alkaline environment facilitates dissolutionand thereby also disintegration of the outer layer since the pH of thealkaline environment is above the pH threshold of the second polymericmaterial, thereby accelerating release of the drug from the formulationonce the outer coating is dissolved and/or disintegrates.

In principle, any pharmacologically acceptable base may be used. Thebase is typically a non-polymeric compound. Suitable bases includeinorganic bases such as sodium hydroxide, potassium hydroxide andammonium hydroxide, and organic bases such as triethanolamine, sodiumbicarbonate, potassium carbonate, trisodium phosphate, trisodium citrateor physiologically tolerated amines such as triethylamine. Hydroxidebases in general, and sodium hydroxide in particular, are preferred.

In embodiments in which the third polymeric material is a fullyneutralised polycarboxylic acid polymer, the base entrapped within theinner layer is usually the base that was used to neutralise the polymerand to adjust the pH of the inner coating preparation to a pH from aboutpH 7.5 to about pH 10 (see below).

In embodiments in which the third polymeric material is a non-ionicpolymer, the inner layer usually comprises either a base, or moretypically a combination of a base and a buffer agent.

The amount of base present in the inner layer would depend at least inpart on the final pH of the inner coating preparation prior to coating agiven batch of cores; the number of cores to be coated in the batch; theamount of the inner coating preparation used in the coating process ofthe batch; and the efficiency of the coating process in terms of theamount of wasted coating preparation.

Buffer Agent

The inner coating preferably comprises at least one buffer agent. Thepurpose of the buffer agent is to provide or increase pH buffer capacityon the underside of the outer layer once intestinal fluid begins topenetrate the outer layer. Without wishing to be bound by any particulartheory, the Inventors believe that the buffer agent increases the buffercapacity in the dissolving inner layer and assists the ionisation anddissolution of the polymer in the outer layer. It is believed that, fora given pH, the higher the buffer capacity, the faster the rate ofpolymer dissolution. In embodiments where there is a base in the innerlayer, the buffer agent helps maintains the alkaline environment underthe outer layer once intestinal fluid penetrates the outer layer.

The buffer agent may be an organic acid such as a pharmacologicallyacceptable non-polymeric carboxylic acid, e.g. a carboxylic acid havingfrom 1 to 16, preferably 1 to 3, carbon atoms. Suitable carboxylic acidsare disclosed in WO2008/135090A. Citric acid is an example of such acarboxylic acid. The carboxylic acids may be used in carboxylate saltform, and mixtures of carboxylic acids, carboxylate salts or both mayalso be used.

The buffer agent may also be an inorganic salt such as an alkali metalsalt, an alkali earth metal salt, an ammonium salt, and a soluble metalsalt. As metals for the soluble metal salts, manganese, iron, copper,zinc and molybdenum can be mentioned. Further preferred, the inorganicsalt is selected from chloride, fluoride, bromide, iodide, phosphate,nitrate, nitrite, sulphate and borate. Phosphates such as potassiumdihydrogen phosphate are preferred over other inorganic buffer salts andorganic acid buffers due to their greater buffer capacity at the pH ofthe coating solution, for example pH 8.

The buffer(s) is usually present in the inner layer in an amount fromabout 0.1 to about 20 wt %, e.g. from about 0.1 to about 4 wt %,preferably from about 0.1 to about 3 wt %, and more preferably about 1wt %, based on the dry weight of the third polymeric material.

Inner Layer

In addition to the buffer agent and/or the base, the inner layer maycomprise conventional excipients for polymer films, including thoseexcipients selected from plasticizers (such a triethyl citrate),anti-tack agents (such as GMS), and surfactants (such as polysorbate80).

The thickness of the inner coating of the core is typically from about10 μm to about 150 μm. As with the outer layer, the thickness of theinner layer is not related to the size of the core but is typicallyequivalent to about 2 mg/cm² to about 10 mg/cm², preferably from about 2mg/cm² to about 8 mg/cm², and most preferably from about 3 mg/cm² toabout 7 mg/cm², based on the dry weight of the third polymeric material,for cores having a diameter from about 0.2 mm to about 30 mm.

Optional Additional Layers

The formulation of the present invention may have an additional (orisolation) layer either between the active core and the inner layerand/or a top coating layer coating the outer layer.

There may be formulations according to the present invention in whichthe composition of the core is incompatible with the delayed releasecoating. In such cases, it may be desirable to include an isolationlayer to separate the core from the coating. For example, the presentinvention embraces embodiments in which the inner layer provides analkaline environment which is thought to assist in the dissolution anddegradation of the outer layer. However, if the core contains a drughaving acidic groups, then the inner layer may be incompatible with thecore. An example of a drug having an acidic group would be 5ASA. In suchcases, it would typically be appropriate to include an isolation layer.

Any suitable isolation layer known to the skilled person can be used. Inone preferred embodiment, the isolation layer comprises a non-ionicpolymer. Suitable non-ionic polymers include methylcellulose (MC);hydroxypropyl cellulose (HPC); hydroxypropyl methylcellulose (HPMC);poly(ethyleneoxide)-graft-polyvinylalcohol; polyvinylpyrollidone (PVP);polyethylene glycol (PEG); and polyvinylalcohol (PVA). Mixtures ofnon-ionic polymers may also be used. HPMC or PVA is preferred. Theisolation layer can additionally comprise polyethylene glycol.

The formulation may also comprise an intermediate layer between theouter and inner layers, provided that the intermediate layer does notaffect adversely the release characteristics of the formulation.However, the outer layer is usually provided in contact with the innerlayer, that is to say the outer layer is usually applied directly on tothe inner layer, i.e. there is usually no intermediate layer separatingthe inner and outer layers.

The Core

The “core” is the solid body on which the inner layer is applied. Thecore may be any suitable dosage form, for example, a tablet, a pellet, agranule, a microparticle, a hard or soft capsule, or a microcapsule. Inpreferred embodiments, the core is a tablet or a capsule.

The core comprises the drug(s). The drug(s) may be contained within thebody of the core, for example within the matrix of a tablet or pellet,or within the contents encapsulated within a capsule. Alternatively, thedrug may be in a coating applied to the core, for example where the coreis a bead of edible material such as sugar, e.g. where the core is inthe form of a nonpareil bead or dragée.

The core may consist of the drug(s) alone, or more usually may consistof the drug(s) and at least one pharmacologically acceptable excipient.In this connection, the core is typically a tablet or pellet andconsists of a mixture of the drug(s) with a filler or diluent material,e.g. lactose or cellulose material such as microcrystalline cellulose; abinder, e.g. polyvinylpyrrolidone (“PVP”) or hydroxypropylmethylcellulose (HPMC); a disintegrant, e.g. croscarmellose sodium (e.g.Ac-Di-Sol™) and sodium starch glycolate (e.g. Explotab™); and/or alubricant, e.g. magnesium stearate and talc. The core may be acompressed granulate comprising at least some of these materials.

The core may be uncoated or, as indicated above, the core may itselfcomprise a coating such as an isolation layer on to which the innerlayer is applied.

The minimum diameter of each core is typically at least about 10⁻⁴ m,usually at least about 5×10⁻⁴ m and, preferably, at least about 10⁻³ m.The maximum diameter is usually no more than 30 mm, typically no morethan 25 mm and, preferably, no more than 20 mm. In preferredembodiments, the core has a diameter from about 0.2 mm to about 25 mm,and preferably from about 0.2 mm to about 4 mm (e.g. for pellets ormini-tablets) or from about 15 mm to about 25 mm (e.g. for certaintablets or capsules). The term “diameter” refers to the largest lineardimension through the core.

The formulation may comprise a plurality of coated cores in order toprovide a single dose of the drug(s), particularly in embodiments inwhich the core is “small”, e.g. having a diameter of less than 5 mm.Multiunit dosage forms comprising coated cores having a diameter of lessthan 3 mm may be preferred.

The present invention has application in a multi-phasic drug releaseformulation comprising at least two pluralities of coated cores, e.g.coated pellets, in the same dosage form, e.g. a capsule, in which thecoated cores of one plurality are differentiated from the coated coresof the or each other plurality by the coating. The coatings may differfrom one plurality to the next in terms of coating thickness orcomposition, e.g. the ratio and/or identity of components. Multi-phasicdrug release formulations would be particularly suitable for suffers ofCrohn's disease affecting different regions along the intestine.

Release from formulations according to the present invention istypically delayed until at least the distal ileum and, preferably, thecolon. Release from certain formulations may also be sustained. However,in preferred formulations, release is pulsatile.

The time between initial exposure to conditions suitable for drugrelease and the start of drug release is known as the “lag time”. Thelag time depends on a number of factors including coating thickness andcomposition and may vary from one patient to the next. Formulationsaccording to the present invention usually display a lag time in colonicconditions of at least 10 minutes. In most embodiments, the lag time isfrom about 10 minutes to about 8 hours. For example, the lag time infaecal slurry at pH 6.8 may be from about 10 minutes to about 2 hours,e.g. from about 30 minutes to about 1.5 hours. Complete release of thedrug may be achieved in no more than 5 hours, e.g. no more than 4 hours,after exposure to these conditions.

A formulation is usually defined as gastric resistant if there is lessthan 10 wt % drug release in acidic media after 2 hours. Formulationsaccording to the present invention typically display far less than 10 wt% drug release in acidic media and may be considered to be gastricresistant. The formulations usually display less than 1 wt % drugrelease in acidic media and, typically, display substantially no drugrelease in acidic media. When starch is combined with an acrylate filmforming material to form the outer layer of the coating for the core,typically less than 5% drug release occurs over 5 hours in conditionssimulating the stomach and small intestine.

In one embodiment, the core is a tablet having a diameter of 15-25 mm.The outer layer preferably comprises a 30:70 mixture of high amylosestarch, e.g. Eurylon™ VII or VI, and a polymethacrylate polymer, e.g.Eudragit™ S, and the inner layer preferably comprises a fullyneutralized polymethacrylate polymer, e.g. Eudragit™ S, applied from aninner coating preparation having a pH of about 8. The core is preferablycoated with the inner layer to a thickness from about 3 to about 7mg/cm² (based on dry weight of the polymethacrylate polymer) to form aninner layer coated core, which is then coated with the outer layer to athickness from about 4 to about 8 mg/cm² (based on dry weight ofpolymethacrylate polymer).

Different Aspects

According to a second aspect of the present invention, there is provideda formulation according to the first aspect for use in a method ofmedical treatment of the human or animal body by therapy.

The core comprises at least one drug. The formulation is usually used toadminister a single drug as the sole therapeutically active component.However, more than one drug may be administered in a single formulation.

The formulation of the present invention is designed to administer awide range of drugs. Suitable drugs include those drugs which are knownfor intestinal administration using known delayed release oralformulations. The present invention may be used to administer drugshaving a local or a systemic effect.

The formulation of the present invention has particular application inthe intestinal administration of a drug comprising at least one acidicgroup such as a carboxylic acid group. Such drugs may be acidic drugs orzwitterionic drugs. An example of such a drug is 5-aminosalicylic acid(5ASA or mesalazine).

The identity of the drug(s) in the formulation obviously depends on thecondition to be treated. In this connection, the formulation hasparticular application in the treatment of IBD (including Crohn'sdisease and ulcerative colitis); IBS; constipation; diarrhea; infection;and carcinoma, particularly colon or colorectal cancer.

For the treatment or prevention of IBD, the formulation may comprise atleast one drug selected from the group consisting of anti-inflammatoryagents (e.g. 5ASA (otherwise known as mesalazine or mesalamine), 4ASA,sulphasalazine and balsalazide); non-steroidal anti-inflammatory agents(e.g. ibuprofen and diclofenac); steroids (e.g. prednisolone; budesonideor fluticasone); immunosuppressants (e.g. azathioprine; cyclosporin; andmethotrexate); antibiotics; and biological agents including peptides,proteins and antibody fragments. Suitable examples of biological agentsinclude alkaline phosphatase and anti-TNF antibodies such as infliximab,adalimumab, certulizumab pegol, golimumab and ustekinumab.

For the treatment or prevention of cancer, the formulation may compriseat least one antineoplastic agent. Suitable antineoplastic agentsinclude fluorouracil; methotrexate; dactinomycin; bleomycin; etoposide;taxol; vincristine; doxorubicin; cisplatin; daunorubicin; VP-16;raltitrexed; oxaliplatin; and pharmacologically acceptable derivativesand salts thereof. For the prevention of colon cancer or colorectalcancer, primarily in patients suffering from colitis, the formulationmay comprise the anti-inflammatory agent, 5ASA.

For the treatment or prevention of IBS, constipation, diarrhea orinfection, the formulation may comprise at least one active agentsuitable for the treatment or prevention of these conditions.

Pharmacologically acceptable derivatives and/or salts of the drugs mayalso be used in the formulation. An example of a suitable salt ofprednisolone is methyl prednisolone sodium succinate. A further exampleis fluticasone propionate.

The present invention has particular application in either the treatmentof IBD (particularly, ulcerative colitis) or the prevention of coloncancer or colorectal cancer (primarily in colitis patients), both using5ASA. It also has application as a portal of entry of drugs into thesystemic circulation via the colon. This is particularly advantageousfor peptide and protein drugs which are unstable in the uppergastrointestinal tract. The present invention may also be utilised forthe purpose of chronotherapy.

In a third aspect of the invention, there is provided a method oftargeting a drug to the colon comprising administering to a patient aformulation as defined above.

In a fourth aspect of the invention, there is provided the use of aformulation as defined above in the manufacture of a medicament for thetreatment or prevention of IBD (particularly ulcerative colitis); IBS;constipation; diarrhea; infection; and cancer.

There is also provided the use of at least one drug selected fromanti-inflammatory agents and steroids in the manufacture of a medicamentcomprising a formulation as defined above for use in the treatment ofIBD. In addition, there is also provided the use of at least oneantineoplastic agent in the manufacture of a medicament comprising aformulation as defined above for use in the treatment of carcinoma.Further, there is also provided use of 5ASA in the manufacture of amedicament comprising a formulation as defined above for use in theprevention of colon cancer or colorectal cancer.

According to a fifth aspect of the present invention, there is provideda method of medical treatment or prevention of IBD or carcinomacomprises administering to a patient a therapeutic amount of aformulation as defined above.

The formulation will typically comprise a therapeutically effectiveamount of the or each drug which may be from about 0.01 wt % to about 99wt %, based on the total weight of the formulation. The actual dosagewould be determined by the skilled person using his common generalknowledge. However, by way of example, “low” dose formulations typicallycomprise no more than about 20 wt % of the drug, and preferably comprisefrom about 1 wt % to about 10 wt %, e.g. about 5 wt %, of the drug.“High” dose formulations typically comprise at least 40 wt % of thedrug, and preferably from about 45 wt % to about 85 wt %, e.g. about 50wt % or about 80 wt %.

Method

According to a sixth aspect of the present invention, there is provideda method of producing a delayed release drug formulation for oraladministration to deliver a drug to the colon according to the firstaspect. The method comprises:

-   -   forming a core comprising a drug;    -   coating the core using an inner coating preparation comprising        the third polymeric material as defined above, in a solvent        system to form an inner coated core;    -   coating the inner coated core with an outer coating preparation        comprising a first polymeric material which is susceptible to        attack by colonic bacteria and a second polymeric material which        has a pH threshold of about pH 5 or above in a solvent system,        to form an outer coated core,        wherein, where the third polymeric material is a non-ionic        polymer, the inner coating preparation comprises at least one        additive selected from the group consisting of a buffer agent        and a base.

The solvent system of the inner coating preparation is preferablyaqueous.

In embodiments where the third polymeric material is an at leastpartially neutralised polycarboxylic acid polymer, said method typicallycomprises dispersing a polycarboxylic acid polymer in a solvent,optionally with a buffer agent, and adding base to at least partiallyneutralise the polycarboxylic acid polymer to form the inner coatingpreparation. In preferred embodiments, the amount of base added is atleast sufficient to fully neutralise the polycarboxylic acid polymer.

In embodiments where the third polymeric material is a non-ionicpolymer, the pH of the inner coating preparation is preferably adjustedprior to coating to be at least 0.5 pH units higher than the pHthreshold of the second polymeric material.

The pH of the inner coating preparation is preferably adjusted to befrom about pH 7.5 to about pH 10, e.g. from about pH 7.5 to about pH8.5, preferably from about pH 7.8 to about pH 8.2, and more preferablyabout pH 8.

The outer coating may be applied using the method described inWO2007/122374A.

Food Effect

The drug release profile from a conventional delayed release dosage formis often dependent on the state of the stomach, i.e. whether the stomachis in the “fed” state or the “fasted” state. In brief, the “fed state”leads to enhanced gastric residence time which can influence t_(lag),i.e. the time before initial release of the drug from the dosage form.In addition, fast in vivo dissolution after leaving the stomach may leadto an increase in C_(max), or the peak blood plasma concentration forthe drug.

The dependency of drug release on the state of the stomach is knowncolloquially as the “food effect” and is the reason why conventionaldosage forms are often to be administered either on an empty stomach, orwith or just after food. Clearly, a significant food effect isundesirable as dictates when an oral dosage form may be administeredwhich could have an adverse effect on patient compliance due topremature drug release.

The fasted and fed states can be simulated in vitro by exposing dosageforms initially to either 0.1N HCl for 2 hours (fasted state) or to FedState Simulated Gastric Fluid (FeSSGF) at pH 5 for 4 hours. After thesimulated fasted or fed states, the tablets are further exposed to Hanksbuffer at pH 6.8 for at least 4 hours which simulates the conditions inthe small intestine. Exposing the tablets for longer than 4 hours, e.g.for 10 hours as in the examples discussed below, can provide anindication of the “robustness” of the tablets.

An example of FeSSGF is described in Jantratid et al (2008) “Dissolutionmedia simulating conditions in the proximal human gastrointestinaltract: An update.” (Pharm. Res. 25(7): 1663-1676). In brief, thisexample of FeSSGF is composed of a mixture (50:50) of milk and aceticacid/sodium acetate buffer and sodium chloride.

By way of example, the Inventors have observed that coated 800 mg 5ASAtablets (coated with single coating of Eudragit S) demonstrate shortert_(lag) when exposed in vitro to this simulated fed state conditionscompared to the simulated fasted state conditions. Earlier initialrelease of 5ASA may result in absorption of the drug in the smallintestine which could lead to an increase in systemic side effects. Asimilar effect is also observed both in vitro and in vivo forLialda®/Mezavant®, a 1200 mg 5ASA tablet formulation from CosmoPharmaceuticals/Shire intended for site specific colonic release of5ASA.

The Inventors have discovered that formulations defined above accordingto the present invention which the outer layer is applied from “semiorganic” coating preparation display similar release profiles after bothfasted and fed simulated gastric conditions. The increase in t_(lag) inthe fed state at least reduces and possibly eliminates the undesirablefood effect, which in turn leads to a reduction in the occurrence ofsystemic side effects and potentially an improvement in patientcompliance since the dose form can be taken at any time, with or withoutfood.

The “semi organic” coating preparation is prepared from an aqueousdispersion of the first polymeric material and an organic (typically,ethanolic) solution of the second polymeric material. Preferred firstand second polymeric materials, and their relative proportions, are asdefined above.

Alcohol Effects

Alcohol-induced premature release (dose dumping) has been observed forcoated 5ASA dosage forms (see Fadda et al (2008) “Impairment of drugrelease from modified release formulations in the presence of alcohol”Int. J. Pharm. 360; 171-176). Preliminary results indicate that, whenexposed to 40% ethanol in 0.1N HCl for 2 hours, formulations accordingto the present invention are more resistant to alcohol-induceddegradation in the stomach and hence do not suffer significantly from analcohol effect. Further studies are proposed to confirm the preliminaryresults.

EXAMPLES

Preferred embodiments of the present invention will now be describedwith reference to the drawings, in which:—

FIG. 1 is a graph comparing drug release as a function of time from 400mg 5ASA tablets coated with (a) a single layer of Eudragit® S alone(Comparative Example 1), (b) a single layer of a 30:70 mixture of starchand Eudragit® S (Comparative Example 2), (c) an inner layer of fullyneutralised Eudragit® S and an outer layer of Eudragit® S (ComparativeExample 3), or (d) an inner layer of fully neutralised Eudragit® S andan outer layer of a 30:70 mixture of starch and Eudragit® S (Example 1),when exposed to 0.1N HCl for 2 hours and then Kreb's buffer (pH 7.4) for8 hours;

FIG. 2 is a graph comparing drug release as a function of time from 400mg 5ASA tablets coated with (a) a single layer of a 30:70 mixture ofstarch and Eudragit® S (Comparative Example 2), (b) an inner layer offully neutralised Eudragit® S and an outer layer of Eudragit® S(Comparative Example 3), or (c) an inner layer of fully neutralisedEudragit® S and an outer layer a 30:70 mixture of starch and Eudragit® S(Example 1), when exposed to faecal slurry at pH 6.8 for 24 hours;

FIG. 3 is a graph comparing drug release as a function of time from 400mg 5ASA tablets coated with (a) an inner layer of fully neutralisedEudragit® S and an outer layer of Eudragit® S (Comparative Example 3),and (b) an inner layer of fully neutralised Eudragit® S and an outerlayer of a 30:70 mixture of starch and Eudragit® S (Example 1), whenexposed to faecal slurry at pH 6.5 for 24 hours;

FIG. 4 is a graph depicting drug release as a function of time from 400mg 5ASA tablets coated with an inner layer of fully neutralisedEudragit® S and an outer layer of a 30:70 mixture of starch andEudragit® S (Example 1), when exposed to Hanks buffer at pH 6.8;

FIG. 5 is a graph comparing drug release as a function of time from 1200mg 5ASA tablets coated with (a) an inner layer of fully neutralisedEudragit® L30D-55 and an outer layer of a 30:70 mixture of starch andEudragit® S (Example 2) and (b) an inner layer of Eudragit® L30D-55 (notneutralised) and an outer layer of a 30:70 mixture of starch andEudragit® S (Comparative Example 4), when exposed to 0.1N HCl for 2hours and then Kreb's buffer (pH 7) for 10 hours;

FIG. 6 is a graph comparing drug release as a function of time fromtablets of Example 2 and Comparative Example 4, when exposed to faecalslurry at pH 6.5 for 24 hours;

FIG. 7 is a graph comparing drug release as a function of time from 1200mg 5ASA tablets coated with (a) an inner layer of neutralized Eudragit®L30D-55 and an outer layer of a 3:1 mixture of guar gum and Eudragit®L30D-55 (Example 3) and (b) an inner layer of Eudragit® L30D-55(not-neutralized) and an outer layer of a 3:1 mixture of guar gum andEudragit® L30D-55 (Comparative Example 5) when exposed to 0.1N HCl for 2hours and then Krebs buffer (pH 7.4) for 10 hours;

FIG. 8 is a graph comparing drug release as a function of time fromtablets of Example 3 and Comparative Example 5 when exposed to 0.1N HClfor 2 hours and then Hanks buffer (pH 6.8) for 10 hours;

FIG. 9 is a graph comparing drug release as a function of time fromtablets of Example 3 and Comparative Example 5 when exposed to faecalslurry at pH 6.5 for 24 hours;

FIG. 10 is a graph comparing drug release, as a function of time from1200 mg 5ASA tablets coated with (a) an isolation layer of polyvinylalcohol (Opadry II 85F), an inner layer of polyvinyl alcohol (Opadry II85F) adjusted to pH 8 and 20% buffer salt, and an outer layer of a blendof Eudragit® S/Eudragit® FS in a 70:30 mixture with starch (Example 4)and (b) an isolation layer made of polyvinyl alcohol (Opadry II 85F) andan outer layer made of a blend of Eudragit® S/Eudragit® FS in a 70:30mixture with starch (Comparative Example 6) when exposed to 0.1N HCl for2 hours and then Krebs buffer (pH 7.4) for 10 hours;

FIG. 11 is a graph comparing drug release as a function of time from1200 mg 5ASA tablets coated with an isolation layer of HPMC, an innerlayer of neutralized Eudragit® S and an outer layer of 30:70starch:Eudragit® S applied from a “semi organic” coating preparation(Example 5) when exposed to FeSSGF at pH 5 for 4 hours (fed state), andthen to Hanks buffer at pH 6.8 for 10 hours (only the Hanks buffer stageis presented);

FIG. 12 is a graph comparing drug release as a function of time from1200 mg 5ASA tablets coated with an isolation layer of HPMC and an outerlayer of 30:70 starch: Eudragit® S applied from a “semi organic” coatingpreparation (Comparative Example 7) when exposed to (a) 0.1N HCl for 2hours (fasted state) or (b) FeSSGF at pH 5 for 4 hours (fed state), andthen to Hanks buffer at pH 6.8 for 10 hours (only the Hanks buffer stageis presented);

FIG. 13 is a graph comparing drug release as a function of time from1200 mg 5ASA tablets coated with an isolation layer of HPMC and an outerlayer of 30:70 starch: Eudragit® S applied from an aqueous coatingpreparation (Comparative Example 8) when exposed to (a) 0.1N HCl for 2hours (fasted state) or (b) FeSSGF at pH 5 for 4 hours (fed state), andthen to Hanks buffer at pH 6.8 for 10 hours (only the Hanks buffer stageis presented);

FIG. 14 is a graph comparing drug release as a function of time from1200 mg 5ASA tablets coated with an isolation layer of HPMC, an innerlayer of neutralized Eudragit® S and an outer layer of 50:50 starch:Eudragit® S applied from a “semi organic” coating preparation (Example6) when exposed to (a) 0.1N HCl for 2 hours (fasted state) or (b) FeSSGFat pH 5 for 4 hours (fed state), and then to Hanks buffer at pH 6.8 for10 hours (only the Hanks buffer stage is presented);

FIG. 15 is a graph comparing drug release as a function of time from 400mg 5ASA tablets coated with an isolation layer of HPMC, an inner layerof neutralized Eudragit® S and an outer layer of 30:70 starch: Eudragit®S applied from a “semi organic” coating preparation (Example 7) whenexposed to (a) 0.1N HCl for 2 hours (fasted state) or (b) FeSSGF at pH 5for 4 hours (fed state), and then to Hanks buffer at pH 6.8 for 10 hours(only the Hanks buffer stage is presented);

FIG. 16 is a graph comparing drug release as a function of time from 400mg 5ASA tablets coated with an inner layer of neutralized Eudragit® Sand an outer layer of 30:70 starch: Eudragit® S applied from a “semiorganic” coating preparation (Example 1) when exposed to (a) 0.1N HClfor 2 hours (fasted state) or (b) FeSSGF at pH 5 for 4 hours (fedstate), and then to Hanks buffer at pH 6.8 for 10 hours (only the Hanksbuffer stage is presented); and

MATERIALS

5-aminosalicylic acid (mesalazine EP) was purchased from CambrexKarlskoga AB, Karlskoga, Sweden. Lactose (Tablettose 80) was purchasedfrom Meggle, Hamburg, Germany. Sodium starch glycolate (Explotab™) waspurchased from JRS Pharma, Rosenberg, Germany. Talc was purchased fromLuzenac Deutschland GmbH, Dusseldorf, Germany. Polyvinylpyrolidon (PVP)was purchased from ISP Global Technologies, Köln, Germany. Magnesiumstearate was purchased from Peter Greven GmbH, Bad Münstereifel,Germany. Eudragit® S 100, Eudragit® L 30 D-55 and Eudragit® FS 30 D wereall purchased from Evonik GmbH, Darmstadt, Germany. Maize starch (NI-460and Eurylon VI or 6) was purchased from Roquette, Lestrem, France.Polysorbate 80, butan-1-ol and sodium hydroxide were all purchased fromSigma-Aldrich, Buchs, Switzerland. Potassium dihydrogen phosphate,glyceryl monostearate (GMS), triethyl citrate (TEC) and ammonia solution(25%) were all purchased from VWR International LTD, Poole, UK.

Preparation of 400 mg 5ASA Tablet Cores

Oblong shaped 400 mg 5ASA tablet cores with dimensions 14.5×5.7 mm wereprepared by fluid bed granulation followed by blending and compression.Each tablet contained 76.9 wt % 5ASA (400 mg; drug); 14.7 wt % lactose(filler); 1.7 wt % PVP (binder); 3.5 wt % sodium starch glycolate(disintegrant); and 2 wt % talc and 1.2 wt % magnesium stearate(lubricants).

The obtained tablet cores were coated as discussed below in Examples 1,8 and 9, and in Comparative Examples 1 to 3 and 9.

Preparation of 1200 mg 5ASA Tablet Cores

Oblong-shaped 1200 mg 5ASA tablet cores (having dimensions 21×10 mm)were prepared by wet granulation. Each tablet contained 85.7 wt % 5ASA(1200 mg), 9.2 wt % microcrystalline cellulose, 1.7 wt % HPMC, 2.9 wt %sodium starch glycolate, and 0.5 wt % magnesium stearate.

The obtained tablet cores were coated as discussed below in Examples 2to 7 and 10, and in Comparative Examples 4 to 7.

Example 1 (Inner Layer of Neutralised Eudragit® S/Outer Layer of 70:30Mixture of Eudragit® S and Starch)

Inner Layer

The inner coating layer was applied using an aqueous preparation ofEudragit® S 100, where the pH is adjusted to pH 8. The composition ofthe inner layer also includes 50% of triethyl citrate (based on drypolymer weight), 10% potassium dihydrogen phosphate (based on drypolymer weight), 10% glyceryl monostearate (GMS; based on dry polymerweight) and 40% polysorbate 80 (based on GMS weight). The pH wasadjusted using 1M NaOH until the pH 8 was obtained. Potassium dihydrogenphosphate and triethyl citrate were dissolved in distilled water,followed by dispersion of the Eudragit® S 100 under mechanicalagitation. The pH of the dispersion was then adjusted to pH 8 with 1MNaOH and left mixing for 1 hour.

A GMS dispersion was prepared at a concentration of 10% w/w. Polysorbate80 (40% based on GMS weight) was dissolved in distilled water followedby dispersion of the GMS. The dispersion was then heated to 75° C. for15 minutes under strong magnetic stirring in order to form an emulsion.The emulsion was cooled at room temperature and under stirring.

The GMS dispersion was added to the neutralised Eudragit® S 100 solutionand the final preparation was coated on to 400 mg 5ASA tablet cores,using a fluid bed spray coating machine until the coating amount reached5 mg polymer/cm². The total solids content of the coating solution is10%. The coating parameters were as follows: spraying rate 20 ml/min/kgtablets, atomizing pressure 0.2 bar and inlet air temperature 40° C.

Outer Layer

The outer coating layer was applied from a mixture of aqueous starchdispersion and an organic Eudragit® S 100 solution.

The aqueous starch dispersion was prepared by dispersing maize starchinto butan-1-ol, followed by water, under magnetic stirring. The ratioof maize starch:butan-1-ol:water was 1:2:22. The resulting dispersionwas heated to boiling and then cooled under stirring overnight. The %solids content of the cooled preparation was calculated based on thefinal weight of the dispersion (considering the evaporation duringheating).

The organic Eudragit® S 100 solution was prepared by dissolvingEudragit® S 100 in 96% ethanol under high speed stirring. The finalsolution contained about 6% polymer solids. The starch dispersion wasadded dropwise to the Eudragit® S 100 solution to obtain a ratio ofstarch:Eudragit® S of 30:70. The mixture was mixed for 2 hours and 20%triethyl citrate (based on total polymer weight) and 5% glycerylmonostearate (GMS, based on total polymer weight) were added and mixedfor further 2 hours.

The GMS was added in the form of a dispersion prepared at aconcentration of 5% w/w. Polysorbate 80 (40% based on GMS weight) wasdissolved in distilled water followed by dispersion of the GMS. Thisdispersion was then heated to 75° C. for 15 minutes under strongmagnetic stirring in order to form an emulsion. The emulsion was cooledat room temperature and under stirring.

The final preparation was coated on to 5ASA tablet cores, previouslycoated with the inner coating layer, using a fluid bed spray coatingmachine until a coating having 7 mg total polymer/cm² was obtained. Thespray coating parameters were as follows: spraying rate 14 ml/min/kgtablets, atomizing pressure 0.2 bar and inlet air temperature 40° C.

Example 2 (Isolation Layer/Inner Layer of Neutralised Eudragit®L30D-55/Outer Layer of 70:30 Mixture of Eudragit® S and Starch)

Isolation Layer

An isolation layer was used containing a mixture of HPMC and 20%polyethylene glycol 6000 (PEG 6000), based on dry polymer weight.

The HPMC was dissolved in water under magnetic stirring and then the PEG6000 was added to form a coating preparation. The coating preparationwas sprayed onto the 1200 mg 5ASA cores, using a pan-coating machine toachieve a coating amount of 3 mg polymer/cm² to form isolation layercoated tablets.

The coating parameters were as follows: Spray rate 3.1 g/min per kgtablet cores; atomizing pressure 0.7 bar; inlet air volume 19 m³/h perkg tablet cores; and product temperature 35° C.

Inner Layer

The inner layer was applied from an aqueous coating preparation ofEudragit® L30D-55, where the pH had been adjusted to pH 8. Thecomposition of the inner layer also included 20% TEC (based on drypolymer weight), 1% potassium dihydrogen phosphate (based on dry polymerweight) and 50% talc (based on dry polymer weight). The pH was adjustedusing 1M NaOH until pH 8 is obtained.

Potassium dihydrogen phosphate and TEC were dissolved in distilled waterfor 15 minutes, after which an Eudragit® L30D-55 dispersion was addedunder mechanical agitation and mixed for 15 minutes. The pH was thenadjusted to pH 8 with 1M NaOH and the solution was left stirring for 1hour. Talc was then added to the solution and mixing continued for afurther 30 minutes to form the inner coating preparation. The innercoating preparation was coated onto the isolation layer coated tablets,using a pan-coating machine until the coating amount reached 5 mgpolymer/cm² to form inner layer coated tablets. The total solids contentof the inner coating preparation was 10% (by weight).

As used herein, the “total solids content” of a suspension, dispersionor other preparation is the total weight of solids used to form thepreparation as a proportion of the total weight of the preparation(solids and solvent). The skilled reader would appreciate thatdissolution of a portion of the solids into the solvent does not affectthe total solids content of the preparation.

The coating parameters were as follows: Spray rate 6.75 g/min per kgtablet cores; atomizing pressure 0.6 bar; inlet air volume 75 m³/h perkg tablet cores; and product temperature 31° C.

Outer Layer

The outer layer was applied from a mixture of an aqueous starchdispersion and an aqueous Eudragit® S 100 solution.

The aqueous starch dispersion was prepared by dispersing maize starchinto butan-1-ol, followed by water, under magnetic stirring. The ratioof maize starch:butan-1-ol:water was 1:2:22. The resulting dispersionwas heated to boiling under reflux and then cooled under stirringovernight.

The aqueous Eudragit® S 100 solution was prepared by dispersingEudragit® S 100 in water under high speed stirring followed by partial(15-20%) neutralization with 1N ammonia solution (obtained by dilutionof 25% ammonia solution).

The aqueous Eudragit® S 100 solution was added to the starch dispersionto obtain a ratio of starch:Eudragit® S of 30:70. The mixture wasstirred for 1 hour and 60% TEC (based on Eudragit® S polymer weight),50% talc (based on Eudragit® S polymer weight), 13.18% iron oxide red(based on Eudragit® S polymer weight) and 2.27% iron oxide yellow (basedon Eudragit® S polymer weight) were added and mixed for further 30minutes.

The final preparation was sprayed onto inner layer coated tablets, in apan-coating machine until 7.14 mg total polymer/cm² was obtained toproduce the coated tablets of Example 2.

The coating parameters were as follows: Spray rate 6.175 g/min per kgtablet cores; atomizing pressure 0.4 bar; inlet air volume 100 m³/h perkg tablet cores; and product temperature 35° C.

Example 3 (Isolation Layer/Inner Layer of Neutralised Eudragit®L30D-55/Outer Layer of 1:3 Mixture of Eudragit® L30D-55 and Guar Gum)

Isolation Layer

The isolation layer is formed by a mixture of HPMC and 20% polyethyleneglycol 6000 (PEG 6000), based on dry polymer weight.

The HPMC polymer was dissolved in water under magnetic stirring and thenPEG 6000 was added to form an isolation layer coating preparation. Thecoating preparation was sprayed onto 1200 mg 5ASA tablet cores, using apan-coating machine to achieve a coating amount of 3 mg polymer/cm² toform isolation layer coated tablets.

The coating parameters were as follows: Spray rate 2.7 g/min. per kgtablet cores; atomizing pressure 0.7 bar; inlet air volume 16 m³/h perkg tablet cores; and product temperature 35° C.

Inner Layer

The inner layer is applied from an aqueous preparation of EudragitL30D-55, where the pH is adjusted to pH 8. The composition of the innerlayer also includes 20% TEC (based on dry polymer weight), 1% potassiumdihydrogen phosphate (based on dry polymer weight), and 50% talc (basedon dry polymer weight). The pH is adjusted using 1M NaOH until pH 8 isobtained.

Potassium dihydrogen phosphate and TEC were dissolved in distilled waterwith stirring for 15 minutes, after which Eudragit L30D-55 dispersionwas added under mechanical agitation and mixed for 15 minutes. The pHwas then adjusted to pH 8 with 1M NaOH and the solution was left mixingfor 1 hour. Talc was then added and mixing was continued for a further30 minutes to form the inner layer coating preparation. The inner layercoating preparation was coated onto the isolation layer coated tabletsusing a pan-coating machine until the coating amount reached 5 mgpolymer/cm² to form inner layer coated tablets. The total solids contentof the final preparation is 10%.

The coating parameters were as follows: Spray rate 2.7 g/min. per kgtablet cores; atomizing pressure 0.6 bar; inlet air volume 30 m³/h perkg tablet cores; and product temperature 31° C.

Outer Layer

The outer layer is applied from a mixture of Eudragit® L30D-55 and guargum.

Eudragit L30D-55 was dissolved in isopropanol. Guar gum was dispersedwith talc in a mixture of water and isopropanol (50:50) for 15 minutesfollowed by homogenization for 5 minutes. The Eudragit L30D-55 solutionwas then added to the guar gum dispersion and the resultant mixture wasstirred for 20 minutes to form the outer layer coating preparation. Thecoating preparation was sprayed onto inner layer coated tablets, in apan-coating machine until the coating amount reached 9.71 totalpolymer/cm² (weight ratio of 1:3 of the dry substances). The coatedtablets were dried at 40° C. for 2 hours to form the tablets of Example3.

The coating parameters were as follows: Spray rate 8.0 g/min per kgtablet cores; atomizing pressure 0.6 bar; inlet air volume 75 m³/h perkg tablet cores; and product temperature 29° C.

Example 4 (Isolation Layer/Inner Layer of PVA with Buffer and Base/OuterLayer of a 70:30 Mixture of Eudragit® S & FS Blend (50:50) and Starch)

Isolation Layer

The isolation layer is composed of polyvinyl alcohol or PVA (Opadry85F).

The polymer was suspended in water under magnetic stirring to achieve aconcentration of 10% solids of the final weight of the dispersion toform an isolation layer coating preparation.

The coating preparation was sprayed onto 1200 mg 5ASA tablet cores,using a pan-coating machine to achieve a coating amount of 2%, based onthe weight of the uncoated tablets to form isolation layer coatedtablets.

The coating parameters were as follows: Spray rate 6.45 g/min per kgtablets; atomizing pressure 0.6 bar; inlet air volume 62.5 m³/h per kgtablet cores; and product temperature 40° C.

Inner Layer

The inner layer is composed of polyvinyl alcohol (Opadry 85F) and 20%potassium dihydrogen phosphate (based on Opadry 85F).

Potassium dihydrogen phosphate was dissolved in water under magneticstirring and then the polyvinyl alcohol (Opadry 85F) was added to form asuspension. The pH of the suspension was then adjusted to pH 8 with 1MNaOH and the mixture was left stirring for 1 hour to form an inner layercoating preparation. The coating preparation was sprayed onto isolationlayer coated tablets using a pan-coating machine until the coatingamount reached 2%, based on the weight of the uncoated tablets, to forminner layer coated tablets.

The coating parameters were as follows: Spray rate 8.2 g/min per kgtablet cores; atomizing pressure 0.7 bar; inlet air volume 62.5 m³/h perkg tablet cores; and product temperature 40° C.

Outer Layer

The outer layer formulation is applied from a mixture of an aqueousstarch dispersion and an aqueous dispersion of a 50:50 blend (based ondry polymer) of Eudragit® S 100 and Eudragit® FS 30D.

The aqueous starch dispersion was prepared by dispersing maize starch(Eurylon 6) into butan-1-ol under magnetic stirring. Water was addedwhile stirring was continued. The ratio of maize starch:butan-1-ol:waterwas 1:2:22. The resulting dispersion was heated to boiling under refluxand then cooled under stirring overnight.

An aqueous dispersion of Eudragit® S 100 was prepared by dispersingEudragit® S 100 in water under high speed stirring followed by partial(15-20%) neutralization with 1N ammonia (formed by dilution of 25%ammonia solution) TEC was added to the dispersion and mixed for 30minutes. Eudragit® FS 30D was added to form a 50:50 blend with theEudragit® S 100 and mixing was continued for a further 30 minutes.

The starch dispersion was added into the dispersion of the Eudragit® S100/Eudragit® FS 30D blend and the mixture was stirred for a further 30minutes. The mixture contained a ratio of starch:Eudragit S 100/EudragitFS 30D blend of 30:70.

A suspension of 50% talc (based on Eudragit® polymer weight), 13.18%iron oxide red (based on Eudragit® polymer weight) and 2.27% iron oxideyellow (based on Eudragit® polymer weight) in water was formed underhigh shear homogenization and this suspension was added to thestarch/Eudragit® blend mixture and mixing was continued for a further 30minutes to form an outer layer coating preparation.

The coating preparation was sprayed onto inner layer coated tablets in apan-coating machine until 5.2 mg Eudragit® polymer blend/cm² wasobtained to form the tablets of Example 4.

The coating parameters were as follows: Spray rate 8.5 g/min per kgtablet cores; atomizing pressure 0.7 bar; inlet air volume 62.5 m³/h perkg tablet cores; and product temperature 41° C.

Example 5 (Isolation Layer/Inner Layer of Neutralised Eudragit® S/OuterLayer of 70:30 Mixture of Eudragit® S and Starch)

Isolation Layer

The isolation layer was formed as in Example 3 although the coatingparameters were as follows: Spray rate 2.33 g/min. per kg tablet cores;atomizing pressure 0.7 bar; inlet air volume 16.3 m³/h per kg tabletcores; and product temperature 33° C.

Inner Layer

The inner coating layer was formed as in Example 1 with the exceptionsthat the composition of the inner layer included 70% (not 50%) oftriethyl citrate (based on dry polymer weight) and 1% (not 10%)potassium dihydrogen phosphate (based on dry polymer weight), that thecoating preparation was coated onto the isolation layer coated 1200 mgtablets using a perforated pan coater machine, and that the coatingparameters were as follows: spraying rate 2.9 g/min/kg tablets,atomizing pressure 0.6 bar, inlet air volume was 16.3 m³/h/kg tabletsand the product temperature was 33° C.

Outer Layer

The outer coating layer was formed as in Example 1 with the exceptionsthat 13.18% iron oxide red (based on Eudragit polymer weight) and 2.27%iron oxide yellow (based on Eudragit polymer weight) were suspended inethanol under high shear homogenisation and this suspension was addedinto the starch and Eudragit mixture and the resultant mixed for thefurther 30 minutes prior to the addition of the GMS, that the coatingpreparation was applied onto the inner layer coated 1200 mg 5ASA tabletsusing a perforated pan coater machine, and that the spray coatingparameters were as follows: spraying rate 3.1 g/min/kg tablets,atomising pressure 0.4 bar, inlet air volume 21.7 m³/h/kg tablets andproduct temperature 34° C.

Example 6 (Isolation Layer/Inner Layer of Neutralised Eudragit® S/OuterLayer of 50:50 Mixture of Eudragit® S and Starch)

Isolation Layer

The isolation layer was formed on 1200 mg 5ASA tablets cores asdescribed in Example 3.

Inner Layer

The inner layer was formed on isolation layer coated 1200 mg 5ASA tabletcores as described in Example 5.

Outer Layer

The outer coating layer was formed on inner layer coated 5ASA tabletcores as described in Example 5 with the exceptions that the ratio ofmaize starch:butan-1-ol:water was 1:1:˜9.5, that the starch:Eudragit Sratio was 50:50, and that the spray parameters were as follows: sprayingrate 7.4 g/min/kg tablets, atomising pressure 0.4 bar, inlet air volume40 m³/h/kg tablets and product temperature 34° C.

Example 7 (Isolation Layer/Inner Layer of Neutralised Eudragit® S/OuterLayer of 70:30 Mixture of Eudragit® S and Starch)

Isolation Layer

The isolation layer was applied to 400 mg 5ASA tablet cores using theprocedure described in Example 3 with the exceptions that a fluid bedspray coater was used and the coating parameters were as follows:spraying rate 3.1 g/min/kg tablets, atomising pressure 0.2 bar, andinlet air temperature 40° C.

Inner Layer

The inner coating layer was applied in the same manner as described inExample 1 with the exception that the composition of the inner layerincluded 70% (not 50%) of triethyl citrate (based on dry polymer weight)and 1% (not 10%) potassium dihydrogen phosphate (based on dry polymerweight). In addition, the inner coating layer preparation was coated onto the isolation layer coated 400 mg 5ASA tablet cores.

Outer Layer

The outer coating layer was formed as in Example 1 with the exceptionsthat 13.18% iron oxide red (based on Eudragit polymer weight) and 2.27%iron oxide yellow (based on Eudragit polymer weight) were suspended inethanol under high shear homogenisation and this suspension was addedinto the starch and Eudragit mixture and the resultant mixed for thefurther 30 minutes prior to the addition of the GMS, and that the outercoating layer preparation was coated on to the inner layer coated 400 mg5ASA tablet cores. The coating parameters were as follows: spraying rate11 ml/min/kg tablets, atomising pressure 0.2 bar, and inlet airtemperature 40° C.

Comparative Example 1 (Single-Layer Coating of Eudragit® S)

The coating layer containing Eudragit® S 100 was applied as an organiccoating composition. The coating composition contained 20% triethylcitrate (based on dry polymer weight), 10% glyceryl monostearate (basedon dry polymer weight) and 40% polysorbate 80 (based on GMS weight).Briefly, triethyl citrate was dissolved in 96% ethanol followed byEudragit® S 100 under mechanical stirring and mixing continued for 1hour.

The GMS was added in the form of a dispersion prepared at aconcentration of 10% w/w. Polysorbate 80 (40% based on GMS weight) wasdissolved in distilled water followed by dispersion of GMS. Thispreparation was then heated to 75° C. for 15 minutes under strongmagnetic stirring in order to form an emulsion. The emulsion was cooledat room temperature and under stirring.

The GMS dispersion was added to the organic Eudragit® S solution and thefinal coating solution was coated on to the 5ASA tablet cores, using afluid bed spray coating machine to achieve a coating amount of 5 mgpolymer/cm². The coating parameters were as follows: spraying rate 16ml/min/kg tablets, atomizing pressure 0.2 bar and inlet air temperature40° C.

Comparative Example 2 (Single-Layer Coating of a 70:30 Mixture ofEudragit® S and Starch)

The coating layer composition contains a mixture of an aqueous starchdispersion and an organic Eudragit® S 100 solution. The aqueous starchdispersion was prepared by dispersing maize starch into butan-1-ol,followed by water, under magnetic stirring. The ratio of maizestarch:butan-1-ol:water was 1:2:22. The resulting dispersion was heatedto boiling and then cooled under stirring overnight. The % solidscontent of the cooled preparation was calculated based on the finalweight of the dispersion (considering the evaporation during heating).

The organic Eudragit® S solution was prepared by dissolution ofEudragit® S 100 in 96% ethanol under high speed stirring. The finalsolution contained about 6% polymer solids. The starch dispersion wasadded dropwise to the Eudragit® S 100 solution to obtain a ratio ofstarch:Eudragit S of 30:70. The mixture was mixed for 2 hours and 20%triethyl citrate (based on total polymer weight) and 5% glycerylmonostearate (based on total polymer weight) were added and the mixturewas mixed for further 2 hours.

The GMS was added in the form of a dispersion prepared at aconcentration of 5% w/w. Polysorbate 80 (40% based on GMS weight) wasdissolved in distilled water followed by dispersion of GMS. Thispreparation was then heated to 75° C. for 15 minutes under strongmagnetic stirring in order to form an emulsion. The emulsion was cooledat room temperature and under stirring.

The final preparation was coated on to the 5ASA tablet cores in a fluidbed spray coating machine until a 7 mg Eudragit® S polymer/cm² wasobtained. The spray coating parameters were as follows: spraying rate 14ml/min/kg tablets, atomizing pressure 0.2 bar and inlet air temperature40° C.

Comparative Example 3 (Inner Layer of Neutralised Eudragit® S/OuterLayer of Eudragit® S)

Inner Layer

The inner coating layer is composed by an aqueous preparation ofEudragit® S 100, where the pH is adjusted to pH 8. The composition ofthe inner layer also includes 50% of triethyl citrate (based on drypolymer weight), 10% potassium dihydrogen phosphate (based on drypolymer weight), 10% glyceryl monostearate (based on dry polymer weight)and 40% polysorbate 80 (based on GMS weight). The pH was adjusted using1M NaOH until the pH 8 is obtained. Potassium dihydrogen phosphate andtriethyl citrate were dissolved in distilled water, followed bydispersion of the Eudragit® S 100 under mechanical agitation. The pH wasthen adjusted to pH 8 with 1M NaOH and left mixing for 1 hour.

A GMS dispersion was prepared at a concentration of 10% w/w. Polysorbate80 (40% based on GMS weight) was dissolved in distilled water followedby dispersion of GMS. This preparation was then heated to 75° C. for 15minutes under strong magnetic stirring in order to form an emulsion. Theemulsion was cooled at room temperature and under stirring.

The GMS dispersion was added to the neutralised Eudragit® S solution andthe final preparation was coated on to 5ASA tablet cores, using a fluidbed spray coating machine until the coating amount reached 5 mgpolymer/cm². The total solids content of the coating solution is 10%.The coating parameters were as follows: spraying rate 20 ml/min/kgtablets, atomizing pressure 0.2 bar and inlet air temperature 40° C.

Outer Layer

The outer coating layer is composed of Eudragit® S 100, applied as anorganic solution. The coating solution contains 20% triethyl citrate(based on dry polymer weight), 10% glyceryl monostearate (based on drypolymer weight) and 40% polysorbate 80 (based on GMS weight). Briefly,triethyl citrate was dissolved in 96% ethanol followed by Eudragit® S100 under mechanical stirring and mixing continued for 1 hour.

A GMS dispersion was prepared at a concentration of 10% w/w. Polysorbate80 (40% based on GMS weight) was dissolved in distilled water followedby dispersion of the GMS. This dispersion was then heated to 75° C. for15 minutes under strong magnetic stirring in order to form an emulsion.The emulsion was cooled at room temperature and under stirring.

The GMS preparation was added to the Eudragit® S 100 solution and thefinal coating solution was coated on to 5ASA tablet cores, previouslycoated with the inner coating layer, using a fluid bed spray coatingmachine to achieve a coating amount of 5 mg Eudragit® S polymer/cm². Thecoating parameters were as follows: spraying rate 16 ml/min/kg tablets,atomizing pressure 0.2 bar and inlet air temperature 40° C.

Comparative Example 4 (Isolation Layer/Inner Layer of Eudragit®L30D-55/Outer Layer of a 70:30 Mixture of Eudragit® S/Starch)

Isolation Layer

The isolation layer is formed from a mixture of HPMC and 20%polyethylene glycol 6000 (PEG6000), based on dry polymer weight.

The polymer was dissolved in water under magnetic stirring and thenPEG6000 was added to form the isolation layer coating preparation. Thecoating preparation was sprayed onto 1200 mg 5ASA tablet cores, using apan-coating machine to achieve a coating amount of 3 mg polymer/cm² toform isolation layer coated tablets.

The coating parameters were as follows: Spray rate 2.7 g/min. per kgtablet cores; atomizing pressure 0.7 bar; inlet air volume 16 m³/h perkg tablet cores; and product temperature 35° C.

Inner Layer

The inner layer is made from a standard (non-neutralised) aqueouspreparation of Eudragit L30D-55. The composition of the inner layer alsoincludes 20% TEC (based on dry polymer weight) and 50% talc (based ondry polymer weight).

Eudragit L30D-55 was diluted in distilled water and then TEC and a talcsuspension were added and mixed for 1 hour to form the inner layercoating preparation. The coating preparation was coated onto isolationlayer coated tablets using a pan-coating machine until the coatingamount reached 5 mg polymer/cm² to form inner layer coated tablets. Thetotal solids content of the final preparation is 10%.

The coating parameters were as follows: Spray rate 6.125 g/min per kgtablet cores; atomizing pressure 0.6 bar; inlet air volume 100 m³/h perkg tablet cores; and product temperature 33° C.

Outer Layer

The outer layer is made from a mixture of aqueous starch dispersion andan aqueous Eudragit® S 100 re-dispersion.

The aqueous starch dispersion was prepared by dispersing maize starchinto butan-1-ol, followed by water, under magnetic stirring. The ratioof maize starch:butan-1-ol:water was 1:2:22. The resulting dispersionwas heated to boiling under reflux and then cooled under stirringovernight.

The aqueous Eudragit® S re-dispersion was prepared by dispersingEudragit® S 100 in water under high speed stirring followed by partial(15-20%) neutralization with 1N ammonia (obtained by dilution of 25%ammonia solution).

The aqueous Eudragit® S re-dispersion was added to the starch dispersionto obtain a ratio of starch:Eudragit S of 30:70. The mixture was stirredfor 1 hour and 60% TEC (based on Eudragit® S polymer weight), 50% talc(based on Eudragit® S polymer weight), 13.18% iron oxide red (based onEudragit® S polymer weight) and 2.27% iron oxide yellow (based onEudragit® S polymer weight) were added and the mixture was stirred for afurther 30 minutes to form an outer layer coating preparation. The outerlayer coating preparation was sprayed onto inner layer coated tablets,in a pan-coating machine until 7.14 mg total polymer/cm² was obtained toproduce the tablets of Comparative Example 4.

The coating parameters were as follows: Spray rate 10.0 g/min; atomizingpressure 0.4 bar; inlet air volume 100 m³/h per kg tablet cores; andproduct temperature 35° C.

Comparative Example 5 (Isolation Layer/Inner Layer of EudragitL30D-55/Outer Layer of a 1:3 Mixture of Eudragit L30D-55/Guar Gum)

Isolation Layer

The isolation layer is applied from a mixture of HPMC and 20%polyethylene glycol 6000 (PEG 6000), based on dry polymer weight.

The HPMC polymer was dissolved in water under magnetic stirring and thenPEG 6000 was added to form the isolation layer coating preparation. Thecoating preparation was sprayed onto 1200 mg 5ASA tablet cores using apan-coating machine to achieve a coating amount of 3 mg polymer/cm² toform isolation layer coated tablets.

The coating parameters were as follows: Spray rate 2.7 g/min per kgtablet cores; atomizing pressure 0.7 bar; inlet air volume 16 m³/h perkg tablet cores; and product temperature 35° C.

Inner Layer

The inner layer was applied from a standard (non-neutralised) aqueouspreparation of Eudragit L30D-55. The composition of the inner layer alsoincluded 20% TEC (based on dry polymer weight) and 50% talc (based ondry polymer weight).

Eudragit L30D-55 was diluted in distilled water and then TEC and talcwere added to form a mixture which was stirred for 1 hour to form aninner layer coating preparation. The coating preparation was coated ontoisolation layer coated tablets using a pan-coating machine until thecoating amount reached 5 mg polymer/cm² to form inner layer coatedtablets. The total solids content of the final preparation is 10% basedon the final weight of the suspension.

The coating parameters were as follows: Spray rate 2.45 g/min per kgtablet cores; atomizing pressure 0.6 bar; inlet air volume 25 m³/h perkg tablet cores; and product temperature 33° C.

Outer Layer

The outer layer contains a mixture of Eudragit L30D-55 and guar gum.

Eudragit L30D-55 was dissolved in isopropanol, and guar gum wasdispersed with talc in a mixture of water and isopropanol (50.50) for 15minutes followed by homogenization for 5 minutes. The Eudragit L30D-55solution was then added to the guar gum dispersion and stirred for 20minutes to form an outer layer coating preparation. The coatingpreparation was sprayed onto inner layer coated tablets in a pan-coatingmachine until 9.71 total polymer/cm² (weight ratio of 1:3 of the drysubstances) was obtained. The coated tablets were dried at 40° C. for 2hours to form the tablets of Comparative Example 5.

The coating parameters were as follows: Spray rate 8.0 g/min per kgtablet cores; atomizing pressure 0.6 bar; inlet air volume 75 m³/h perkg tablet cores; and product temperature 29° C.

Comparative Example 6 (Isolation Layer/Outer Layer of a 70:30 Mixture ofEudragit® S & FS Blend (50:50) and Starch)

Isolation Layer

The isolation layer was composed of polyvinyl alcohol (Opadry 85F).

The polyvinyl alcohol (Opadry 85F) was suspended in water under magneticstirring to achieve a concentration of 10% solids based on the finalweight of the suspension to form an isolation layer coating preparation.

The coating preparation was sprayed onto 1200 mg 5ASA tablet cores usinga pan-coating machine to achieve a coating amount of 2%, based on theweight of the uncoated tablets, to form isolation layer coated tablets.

The coating parameters were as follows: Spray rate 6.45 g/min per kgtablets; atomizing pressure 0.6 bar; inlet air volume 62.5 m³/h per kgtablet cores; and product temperature 40° C.

Outer Layer

The outer layer formulation is applied from a mixture of an aqueousstarch dispersion and an aqueous dispersion of a 50:50 blend (based ondry polymer) of Eudragit® S 100 and Eudragit® FS 30D.

The aqueous starch dispersion was prepared by dispersing maize starch(Eurylon 6) into butan-1-ol under magnetic stirring. Water was addedwhile stirring was continued. The ratio of maize starch:butan-1-ol:waterwas 1:2:22. The resulting dispersion was heated to boiling under refluxand then cooled under stirring overnight.

An aqueous dispersion of Eudragit® S 100 was prepared by dispersingEudragit® S 100 in water under high speed stirring followed by partial(15-20%) neutralization with 1N ammonia (formed by dilution of 25%ammonia solution) TEC was added to the dispersion and mixed for 30minutes. Eudragit® FS 30D was added to form a 50:50 blend with theEudragit® S 100 and mixing was continued for a further 30 minutes.

The starch dispersion was added into the dispersion of the Eudragit® S100/Eudragit® FS 30D blend and the mixture was stirred for a further 30minutes. The mixture contained a ratio of starch:Eudragit S 100/EudragitFS 30D blend of 30:70.

A suspension of 50% talc (based on Eudragit® polymer weight), 13.18%iron oxide red (based on Eudragit® polymer weight) and 2.27% iron oxideyellow (based on Eudragit® polymer weight) in water was formed underhigh shear homogenization and this suspension was added to thestarch/Eudragit® blend mixture and mixing was continued for a further 30minutes to form an outer layer coating preparation.

The coating preparation was sprayed onto isolation layer coated tabletsin a pan-coating machine until 5.2 mg Eudragit® polymer blend/cm² wasobtained to form the tablets of Example 4.

The coating parameters were as follows: Spray rate 8.5 g/min per kgtablet cores; atomizing pressure 0.7 bar; inlet air volume 62.5 m³/h perkg tablet cores; and product temperature 41° C.

Comparative Example 7 (Isolation Layer/Outer Layer of 30:70Starch:Eudragit S)

Isolation Layer

Isolation layer coated 1200 mg 5ASA tablet cores were prepared as inComparative Example 4.

Outer Layer

The outer coating layer was applied to the inner coated tablet coresfrom a mixture of aqueous starch dispersion and an organic Eudragit® S100 solution.

The aqueous starch dispersion was prepared by dispersing maize starchinto butan-1-ol, followed by water, under magnetic stirring. The ratioof maize starch:butan-1-ol:water was 1:2:22. The resulting dispersionwas heated to boiling and then cooled under stirring overnight. The %solids content of the cooled preparation was calculated based on thefinal weight of the dispersion (considering the evaporation duringheating).

The organic Eudragit® S 100 solution was prepared by dissolvingEudragit® S 100 in 96% ethanol under high speed stirring. The finalsolution contained about 6% polymer solids. The starch dispersion wasadded dropwise to the Eudragit® S 100 solution to obtain a ratio ofstarch:Eudragit® S of 30:70.

The mixture was mixed for 2 hours and 20% triethyl citrate (based ontotal polymer weight) and 5% glyceryl monostearate (GMS, based on totalpolymer weight) were added and mixed for further 2 hours. 13.18% ironoxide red (based on Eudragit polymer weight) and 2.27% iron oxide yellow(based on Eudragit polymer weight) were suspended in ethanol under highshear homogenization and this suspension was added into the starch andEudragit mixture and mixed for further 30 minutes.

The GMS was added in the form of an emulsion prepared at a concentrationof 5% w/w. Polysorbate 80 (40% based on GMS weight) was dissolved indistilled water followed by dispersion of the GMS. This dispersion wasthen heated to 75° C. for 15 minutes under strong magnetic stirring inorder to form an emulsion. The emulsion was cooled at room temperatureand under stirring. The final preparation was coated onto the isolationlayer coated tablet cores using a perforated pan coater machine until acoating having 5 mg Eudragit® S polymer/cm² was obtained. The spraycoating parameters were as follows: spraying rate 3.1 g/min/kg tablets,atomizing pressure 0.4 bar, inlet air volume 21.7 m³/h/kg tablets andproduct temperature 34° C.

Comparative Example 8 (Isolation Layer/Outer Layer of 30:70Starch:Eudragit S)

Isolation layer coated 1200 mg 5ASA tablet cores were prepared as inComparative Example 4.

Outer Layer

The outer layer is applied from a mixture of an aqueous starchdispersion and an aqueous Eudragit S 100 re-dispersion.

The aqueous starch dispersion was prepared as described in Example 1.

The aqueous Eudragit S re-dispersion was prepared by dispersing EudragitS 100 in water under high speed stirring followed by partialneutralisation with 1N NH₃ obtained by dilution of 25% ammonia.

The aqueous Eudragit S re-dispersion was added to the starch dispersionto obtain a ratio of starch to Eudragit S of 30:70. This was mixed for 1hour and 60% TEC (based on Eudragit S polymer weight), 50% talc (basedon Eudragit S polymer weight), 13.18% iron oxide red (based on EudragitS polymer weight) and 2.27% iron oxide yellow (based on Eudragit Spolymer weight) were added and mixed for a further 30 minutes to formthe outer layer coating preparation.

The outer layer coating preparation was sprayed on to inner layer coated1200 mg 5ASA tablet cores in a pan coating machine until 7.14 mg totalpolymer/cm² was obtained. The coating parameters were as follows: sprayrate 6.175 g/min·kg tablet cores, atomising pressure 0.4 bar, inlet airvolume 100 m³/h/kg tablet cores and product temperature 35° C.

Drug Release Test #1—Effect of pH Alone

In vitro dissolution studies were performed on a USP type II apparatususing a paddle speed of 50 rpm and a media temperature of 37±0.5° C.Tablets were first tested in 0.1 M HCl for 2 hours followed by 8 or 10hours in Krebs buffer (pH 7.4). The pH of the buffer was stabilized at7.4±0.05 by continuously sparging with 5% CO₂/95% O₂. Absorbancemeasurements were taken at 5 minute intervals, with an absorbancewavelength of 301 nm in HCl and 330 nm in Krebs buffer. The compositionper liter of Krebs buffer is 0.16 g of KH₂PO₄, 6.9 g of NaCl, 0.35 gKCl, 0.29 g MgSO₄.7H₂O, 0.376 g CaCl₂.2H₂O and 2.1 g NaHCO₃. Only themeasurements taken at 15 minute intervals are depicted in FIG. 1.

Drug Release Test #2—Faecal Slurry at pH 6.8

The fermentation assays used to test the formulations were based on themethod described by Hughes et al. (“In vitro fermentation of oat andbarley derived beta-glucans by human faecal microbiota” FEMS Microbiol.Ecol.; 2008; 64(3); pp 482 to 493).

The basal medium used to allow bacterial growth was prepared accordingto Hughes et al and mixed in a ratio of 1:1 with a faecal slurry, whichwas prepared by homogenizing fresh human faeces (3 different donors) inphosphate buffered saline (pH 6.8) at a concentration of 40% w/w. Thefinal concentration of the prepared faecal slurry (diluted with basalmedium) was 20% w/w. The donors had not received antibiotic treatmentfor at least three months before carrying out the studies using theslurry.

Tablets were tested in 210 ml of faecal slurry adjusted to the requiredpH and under continuous stirring. The tests were carried out in ananaerobic chamber (at 37° C. and 70% RH). The samples were analysed for5ASA content by HPLC with a UV detector.

Drug Release Test #3—Faecal Slurry at pH 6.5

As for Drug Release Test #2 but the pH of the faecal slurry wasmaintained at pH 6.5.

Drug Release Test #4—Dissolution in Hanks Buffer pH 6.8

In vitro dissolution studies were performed on a USP type II apparatususing a paddle speed of 50 rpm and a media temperature of 37±0.5° C.Tablets were first tested in 0.1 M HCl for 2 hours followed by 8 or 10hours in Hanks buffer (pH 6.8). The pH of the buffer was stabilized at6.8±0.05 by continuously sparging with 5% CO₂/95% O₂. Absorbancemeasurements were taken at 5 minute intervals, with an absorbancewavelength of 301 nm in HCl and 330 nm in Hanks buffer pH 6.8. Thecomposition per liter of Hanks buffer is 0.06 g of KH₂PO₄, 0.06 gNa₂HPO₄.2H₂O, 8.0 g NaCl, 0.4 g KCl, 0.2 g MgSO₄.7H₂O, 0.139 gCaCl₂.2H₂O and 0.350 g NaHCO₃.

Drug Release Test #5—Simulated Fed/Fasted State then Hanks Buffer pH 6.8

In vitro dissolution studies were performed on a USP type II apparatususing a paddle speed of 50 rpm and a media temperature of 37±0.5° C.When simulating the “fasted” state, the studies were carried out in themanner described for Drug Release Test #4.

When simulating the “fed” state, the tablets were first tested in FedState Simulated Gastric Fluid (FeSSGF) at pH 5.0 for 4 h followed by 10hours in Hanks buffer (pH 6.8). The FeSSGF was as described in Jantridet al (2008) supra.

Drug Release Test #5—40% Ethanol (v/v) in 0.1N HCl

Coated tablets were tested in a disintegration apparatus using ahydro-alcoholic solution of 0.1N HCl (40% ethanol) for 2 hours. At theend of 2 hours, the morphology of the tablets was evaluated visually forpresence of cracks and/or swelling.

Results

The results presented in FIGS. 1 to 4 demonstrate that the coatedtablets according to the present invention are significantly superior tothe tablets of the comparative examples. In this connection, anacceleration of drug release is observed for the tablets according tothe present invention, both at a pH higher (pH 7.4) than the pHthreshold (pH 7) of the second polymeric material and at a lower pH (pH6.8 or pH 6.5) than the pH threshold, relative to the comparatortablets.

In aqueous solution at pH 7.4 (drug release test #1; FIG. 1), there wasno release of 5ASA from any of the tablets tested in the 2 hours thatthe tablets were exposed to simulated gastric conditions. However, itshould be noted that, once the tablets were exposed to pH 7.4, initialrelease of 5ASA from Example 1 tablets occurred significantly earlierthan from Comparative Example 1 (which is a conventional site-specificcolonic release formulation) and from Comparative Example 2 (which is asite-specific colonic release formulation described in WO2007/122374).The profile of release of 5ASA from Example 1 closely followed that forComparative Example 3. The similar release profiles may be explained bythe similarities in the formulations themselves (Example 1 differingonly in the presence of starch in the outer coating) and the absence ofany colonic enzymes in the surrounding medium to digest the starch.

In faecal slurry at pH 6.8 (drug release test #2; FIG. 2), initialrelease of 5ASA from the tablets of Example 1 occurred after about 1hour, and complete release occurred in about 3 hours after initialrelease. In contrast, initial release from the tablets of bothComparative Examples 2 and 3 occurred after about 2 hours, withsignificant release from the tablets of Comparative Example 3 occurringonly after 6 hours. In addition, while the tablets of ComparativeExample 2 provided complete release after about 5 hours, the tablets ofComparative Example 3 provided less than 40% release over 24 hours. Theresults indicate that the presence of the inner soluble layeraccelerates drug release under colonic conditions from tablets having anouter layer comprising a mixture of starch and Eudragit S. The resultsalso indicate that, without the polysaccharide in the outer layer(Comparative Example 3), release under colonic conditions is notcomplete.

In faecal slurry at pH 6.5 (drug release test #3; FIG. 3), initialrelease of 5ASA from the tablets of Example 1 occurred after about 2hours, whereas initial release from the comparator tablets occurred onlyafter about 8 hours. In addition, even though the pH of the surroundingmedium was significantly below the pH threshold of Eudragit S, tabletsaccording to Example 1 had release about 40% of the 5ASA after about 8hours. In contrast, the tablets of Comparative Example 3 had releasedless than 10% of the 5ASA after 24 hours. These results indicate thatthe presence of starch in the outer layer enables release of asignificant amount of the active when exposed to colonic enzymes eventhough the pH of the surrounding medium is well below the pH thresholdof the second polymeric material.

The skilled reader would appreciate that, even though the integrity ofcoating in Example 1 was compromised, not all of the active was releasedafter 8 hours. The Inventors believe that this is because the test is invitro. In vivo, the tablets would be subjected to mechanical pressureapplied as a result of the motility of the colon and which shouldcontribute to complete disintegration of the tablets.

The Inventors have also observed that less than 10% of 5ASA is releasedfrom tablets of Example 1 when exposed to aqueous solution at pH 6.8 for24 hours (see drug release test #4; FIG. 4). This result demonstratesthe requirement for the presence of colonic enzymes in the surroundingmedium to achieve significant release of the active from tabletsaccording to the present invention and the resistance to the conditionsof the small intestine, thereby efficiently preventing premature drugrelease.

Accelerated drug release under colonic conditions is also observed forformulations of the present invention where the inner layer comprisesneutralised Eudragit® L30D-55 and the outer layer comprises a 30:70mixture of starch/Eudragit® S 100 when compared with equivalentformulations in which the inner layer has not been neutralised. Asindicated in FIG. 5, no release is observed from either formulation whenexposed to 0.1 M HCl for 2 hours. However, when exposed to Krebs bufferat pH 7.4, initial release from the formulation according to the presentinvention (Example 2) is observed after 30 minutes whereas initialrelease from the comparative formulation (Comparative Formulation 4)does not occur until about 150 minutes. Similar acceleration of initialrelease is observed when these formulations are exposed to faecal slurryat pH 6.5 with initial release from the tablets having the neutralisedinner layer (Example 2) taking place after about 2 hours in contrast toabout 4 hours for the tablets with the non-neutralised inner layer(Comparative Example 4) (FIG. 6).

Formulations according to the present invention also demonstrate a clearadvantage over the formulation exemplified in U.S. Pat. No. 5,422,121.In this regard, the Inventors reproduced as closely as possible theformulation of Example 2 of U.S. Pat. No. 5,422,121 in which a tabletcore was coated first with an inner layer of Eudragit® L30D and thenwith an outer layer of a 1:3 mixture of Eudragit® L30D and guar gum(Comparative Example 5), and compared drug release over time indifferent conditions from this formulation with an equivalentformulation in which the Eudragit® L30D of the inner layer was fullyneutralised according to one embodiment of the present invention(Example 3). Under all of the colonic conditions tested, initial drugrelease was accelerated for the formulation having the neutralised innerlayer (see FIGS. 7 to 9).

Formulations having an inner layer comprising a non-ionic polymer, abase and a buffer agent also demonstrate accelerated initial drugrelease when compared with equivalent formulations in which the innerlayer does not contain a base or a buffer agent. In this regard, theInventors have demonstrated that initial release may be reduced from 4hours to 3 hours when exposed to Krebs buffer in embodiments having aninner PVA polymer layer and an outer layer comprising a 70:30 mixture ofEudragit® S/Eudragit® FS (50:50) blend and starch, provided that theinner layer contains a base and a buffer agent (FIG. 10).

Incomplete drug release was observed in some of the test runs after 10hours at colonic conditions (see in particular FIGS. 8 and 9). TheInventors note that this observation may be explained by the fact thathigh dosage (1200 mg) tablets were tested in these runs and sinkconditions could not be achieved with the low capacity buffers (Krebsand Hanks buffers) used, or with the limited volume (210 ml) of faecalslurry used.

In contrast, the tablets of Examples 5 to 7 do not exhibit significantrelease prematurely when exposed to the simulated fed state conditionsover the duration of the test (FIGS. 11, 14, 15). In addition, thetablets of Example 7 do not demonstrate a significant “food effect” whenexposed to the simulated fed and fasted states over the duration of thetests (FIG. 15). In other words, not only do these tablets demonstrateless than 10% drug release by the end of the tests, but the releaseprofiles in both the simulated fed and fasted states are either verysimilar (Example 7; FIG. 15) or almost identical (Example 6; FIG. 14).

The results appear to support the conclusion a food effect associatedwith coated 5ASA tablets may be reduced or even eliminated by providingthe tablets with a coating according to the present invention. Inparticular, the results appear to indicate that applying the outercoating using a “semi organic” coating preparation rather than anaqueous coating preparation can eliminate the food effect (Example 1;FIG. 16).

It can be seen therefore that the delayed release formulation accordingto the present invention is significantly superior to comparativeformulations.

Whilst the invention has been described with reference to a preferredembodiment, it will be appreciated that various modifications arepossible within the spirit or scope of the invention as defined in thefollowing claims.

In this specification, unless expressly otherwise indicated, the word‘or’ is used in the sense of an operator that returns a true value wheneither or both of the stated conditions is met, as opposed to theoperator ‘exclusive or’ which requires that only one of the conditionsis met. The word ‘comprising’ is used in the sense of ‘including’ ratherthan in to mean ‘consisting of’. All prior teachings acknowledged aboveare hereby incorporated by reference. No acknowledgement of any priorpublished document herein should be taken to be an admission orrepresentation that the teaching thereof was common general knowledge inAustralia or elsewhere at the date hereof.

The invention claimed is:
 1. A delayed release drug formulation for oraladministration to deliver a drug to the colon of a subject, saidformulation comprising: a core and a coating for the core, the corecomprising a drug and the coating comprising an outer layer and an innerlayer, wherein the outer layer comprises a mixture of a first polymericmaterial which is susceptible to attack by colonic bacteria and a secondpolymeric material which has a pH threshold at about pH 6 or above,wherein the inner layer comprises a third polymeric material which issoluble in intestinal fluid or gastrointestinal fluid, said thirdpolymeric material being a polycarboxylic acid polymer selected from thegroup consisting of polymethacrylate; cellulose acetate phthalate (CAP);polyvinyl acetate phthalate (PVAP); hydroxypropyl methylcellulosephthalate (HPMCP); hydroxypropyl methylcellulose acetate succinate(HPMC-AS); xanthan gum; and shellac, wherein said polycarboxylic acidpolymer is at least partially neutralized such that at least 90% of thecarboxylic acid groups are in the form of carboxylate anions, andwherein the at least partially neutralized polycarboxylic acid polymeris the sole film-forming polymer in the inner layer.
 2. The formulationof claim 1, wherein said polycarboxylic acid polymer is fullyneutralized.
 3. The formulation of claim 1, wherein said secondpolymeric material is based on the same polycarboxylic acid polymer assaid third polymeric material, and the third polymeric material has ahigher degree of neutralization than the second polymeric material. 4.The formulation of claim 1, wherein said third polymeric material is anat least partially neutralized co-polymer of (meth)acrylic acid and a(meth)acrylic acid C₁₋₄ alkyl ester.
 5. The formulation of claim 1,wherein said third polymeric material is a fully neutralized co-polymerof (meth)acrylic acid and (meth)acrylic acid methyl ester.
 6. Theformulation of claim 1, wherein the second polymeric material is a blendof at least two different polymers having a pH threshold of about pH 5and above.
 7. The formulation of claim 6, wherein the at least twodifferent polymers in the blend are different polymethacrylate polymers.8. The formulation of claim 6, wherein there are two different polymersin the blend in a weight ratio from about 40:60 to about 60:40.
 9. Theformulation of claim 1, wherein the first and second polymeric materialsare present the outer layer in a weight ratio of up to about 60:40. 10.The formulation of claim 1, wherein the first and second polymericmaterials are present in the outer layer in a weight ratio from about25:75 to about 35:65.
 11. The formulation of claim 1, wherein the firstand second polymeric materials are present in the outer layer in aweight ratio from about 40:60 to about 60:40.
 12. A method of producingthe delayed release drug formulation for oral administration to delivera drug to the colon as claimed in claim 1, said method comprising:forming the core comprising the drug; coating the core with an innercoating preparation comprising the third polymeric material in a solventsystem to form an inner coated core; and coating the inner coated corewith an outer coating preparation comprising the first polymericmaterial and the second polymeric material to form an outer coated core.13. The method of claim 12, wherein the solvent system of the innercoating preparation is aqueous.
 14. The method of claim 12, wherein saidthird polymeric material is said polycarboxylic acid polymer that is atleast partially neutralized, said method comprising dispersing apolycarboxylic acid polymer in a solvent, optionally with the bufferagent, and adding the base to at least partially neutralize thepolycarboxylic acid polymer to form the inner coating preparation. 15.The method of claim 14, wherein the amount of base added is at leastsufficient to neutralize at least 10% of the carboxylic acid groups inthe polycarboxylic acid polymer.
 16. The method of claim 14, wherein theamount of base added is more than sufficient to fully neutralize thepolycarboxylic acid polymer.
 17. The method of claim 12, wherein saidthird polymeric material is said non-ionic polymer, the pH of the innercoating preparation being adjusted prior to coating to be at least 0.5pH units higher than the pH threshold of the second polymeric material.18. The method of claim 12, wherein the pH of the inner coatingpreparation is adjusted to be from about pH 7.5 to about pH
 10. 19. Themethod of claim 12, wherein the base is selected from the groupconsisting of hydroxide bases, alkali metal bicarbonates, alkali metalcarbonates, alkali metal phosphates, alkali metal citrates, orphysiologically tolerated amines.
 20. The method of claim 12, whereinthe base is a hydroxide.
 21. The method of claim 12, wherein the base issodium hydroxide.
 22. The formulation of claim 6, wherein there are twodifferent polymers in the blend in a weight ratio of about 50:50. 23.The formulation of claim 1, wherein the first and second polymericmaterials are present in the outer layer in a weight ratio of about30:70.
 24. The formulation of claim 1, wherein the first and secondpolymeric materials are present in the outer layer in a weight ratio ofabout 50:50.
 25. The formulation of claim 1, wherein said inner layerfurther comprises at least one additive selected from the groupconsisting of a buffer agent, which is a non-polymeric organic acid oran inorganic salt, and a base, which is a non-polymeric base.
 26. Theformulation of claim 25, wherein the inner layer comprises the bufferagent and the base.
 27. The formulation of claim 25, wherein the innerlayer comprises a buffer agent and wherein the buffer agent is selectedfrom the group consisting of a carboxylic acid having from 1 to 16carbon atoms, an alkali metal salt, an alkali earth metal salt, anammonium salt and a soluble metal salt.
 28. The formulation of claim 25,wherein the inner layer comprises a buffer agent and wherein the bufferagent is a phosphate salt.
 29. The formulation of claim 25, wherein theinner layer comprises a buffer agent and wherein the buffer agent ispotassium dihydrogen phosphate.
 30. The formulation of claim 25, whereinthe inner layer comprises a buffer agent and wherein the buffer agent ispresent in the inner layer an amount from about 0.1 wt % to about 20 wt% based on the dry weight of the third polymeric material.
 31. Theformulation of claim 25, wherein the inner layer comprises a base andwherein the base is selected from the group consisting of hydroxidebase, alkali metal bicarbonate, alkali metal carbonate, alkali metalphosphate, alkali metal citrate, and physiologically tolerated amine.32. The formulation of claim 25, wherein the inner layer comprises abase and wherein the base is a hydroxide base.
 33. The formulation ofclaim 25, wherein the inner layer comprises a base and wherein the baseis sodium hydroxide.